Email System Documentation

  1. Add your sender domain by clicking the [+] button on the Tools/Domains page.
  2. Add the DNS records displayed to the DNS control panel of your domain's registrator. Each registrator has its own interface for that, so in case of any doubt don't hesitate to contact our friendly support to help. Take a 10-15 minute break to ensure that the new records are updated in the distributed DNS database, then click the Verify link near the domain on the Tools/Domains page. The green checkmarks will show you that your domain is properly set up. Otherwise please double-check your records (press the setup icon to view the required records). If everything is ok, just allow some time for records propagation (usually it takes no more than half an hour, but in certain rare cases, this can take as much as 48 hours). The domain is ready for sending when all the checkmarks show up.

  3. Send the first email to your own domain using SMTP or Web API. Your new account by default has a "Free" plan which allows you to test our services by sending up to 100 emails per day to any of the domains you’ve added and verified.

  4. Change your subscription plan to any paid one to be able to send to all domains, not only just your own ones. You can start with the "StartUp 6K" plan which is free for 4 months after registration. 

Your setup is now complete!

We also recommend that you find out more about our Web API capabilities. It allows you to get real time event notifications, create and manage templatesunsubscribed recipients and more. You may also be interested in familiarising yourself with other articles from our knowledge base and integration libraries.

If you have any further questions, do not hesitate to contact our most helpful tech support.

We make every effort to ensure the highest possible delivery rates. While the delivery result of any one particular email is not always guaranteed (for many reasons, including not only the letter itself and its originating server reputation, but also certain settings of the target mail server), we at UniOne consistently maintain a delivery rate as high as 99.8%. To achieve this excellent  performance we use the following techniques and practices.

  1. We conform to all major standards of email authentication, including SPFDKIM and DMARC. The same is required of our customers. For this reason we ensure that all our clients verify their domain ownership by adding the required records to the Domain Naming Service (DNS) database. This one-time procedure is necessary to guarantee that your sender reputation is in no way influenced by other customers of our service. The validity of your DNS records will be automatically re-checked on a schedule, and we will inform you if something goes wrong.

  2. We constantly monitor all major black lists and sender reputation services for our IP addresses. In case a match is found, we promptly investigate the reason and delist the shared IP address. If you are using a dedicated IP address, we will immediately let you know so that you are able to delist the address yourself.

  3. Delivery of all your emails to addressee domains is monitored in real time. In case a particular domain starts rejecting all your emails, we will temporarily pause outbound email to this domain and notify you via web hook API and by email. We cannot investigate every such occurrence, but we do provide the tools you need to locate the cause. However, in the case of transaction emails such events are extremely rare. In case of mass mailing they can also be avoided, with due respect to certain "email sanity" practices.

  4. We make use of the Feedback Loop (FBL) services provided by most major email services. This allows us to track not only the delivery result for any particular letter, but also to be notified when an addressee hits the SPAM button. Such events are forwarded to the customer via webhook and made visible in delivery statistics. We also block sending further emails to this address, to keep your sender reputation safe.

  5. An unsubscribe link is added to every letter by default. Omitting such link would result in high numbers of spam complaints, which in turn could severely downgrade your sender reputation and delivery rate. However, you also have the  option to change the appearance of our default unsubscribe block or even implement your own unsubscribe mechanism and notify us via an API call.

All of the above measures help us maintain high delivery rates.

Here you can find several articles describing UniOne internals in depth.

At times, you may need to send an email to several addresses at once, so that each addressee could see other recipients in To: or CC: fields. Or, alternatively, you may want to send someone a “blind copy”, or BCC. Here, we’ll show you how this can be accomplished.

Sending copies via Web API

Sending copies differs from regular sending in that the email parameter indicates the primary recipient, while the "To:" and "CC:" headers contain other addresses. For this, we need to specify the necessary headers "To:" and "CC:" in the headers parameter. UniOne sends these headers "as is", without changing anything about them (only MIME encoding them if necessary).

Let's consider a simple example when you need to send a letter to John at user@example.com along with a copy to Mary at cc@example.org. this case, the recipients and headers parameters of the email/send method should be as follows:

  "recipients": [
    {"email":"user@example.com"},
    {"email":"сс@example.org"}
  ],
  "headers": {
    "To": "John <user@example.com>",
    "CC": "Mary <cc@example.org>"
  }

Here's a more complex example. We send a letter to Miguel and José, with copies to Helen and Habib, plus a blind copy to bcc@example.net:

  "recipients": [
    {"email":"to_user1@example.com"},
    {"email":"to_user2@example.com"},
    {"email":"copy1@example.org"},
    {"email":"copy2@example.org"},
    {"email":"bcc@example.net"}
  ],
  "headers": {
    "To": "Miguel <to_user1@example.com>, José <to_user2@example.com>",
    "CC": "Helen <copy1@example.org>, Habib <copy2@example.org>"
  }

Please note the following:

  • The names for "To" and "CC" addresses in the headers can be sent “as is”, without MIME encoding of any international characters.
  • It is important to keep in mind that substitutions in a letter can be different for each recipient. If you want all addressees to receive the same text, either use the same substitutions for each one, or use the global_substitutions parameter instead of personal substitutions.
  • Links for tracking email opens and clicks, as well as the unsubscribe link, will always be unique for each recipient.
  • Your account will be charged for each email specified in the recipients array.

There are several restrictions when sending copies with UniOne:

  • You cannot specify a "CC" header without a "To" header – this will result in a sending error. The “To” header without “CC” is allowed.
  • The number of addresses in the "To" header is limited to ten; the same restriction applies to the "CC" header. There can also be a maximum of ten blind copies.
  • If the address from the email parameter is not listed as either “To” or “CC” (i.e., it is used to create a blind copy), then this address can only be on your own domain already verified in UniOne. You cannot send blind copies to domains other than those you own. Unfortunately, we have to enforce this rule to prevent email phishing.

Sending copies via SMTP API

By default, when sending via SMTP, UniOne does not strictly adhere to the RFC specifications. Instead, it sends each recipient from the “To” and “CC” headers their own copy of the letter with a single email address in the final “To” header, which matches the real address of the recipient.

If you need strict compliance with the SMTP standard, i.e. emails being sent without changing the To: and CC: MIME headers (for example, to send regular and blind copies with CC and BCC), you must enable strict mode by setting the strict parameter to true in the X-UNIONE header, or contact technical support to enable strict=true for all your emails without having to pass an additional parameter in the header.

Unlike the email/send Web API call, when sending via SMTP, you are responsible for the correct MIME encoding of the headers. By default, you’ll be charged for each address in the To or CC header; in strict mode – for each recipient in the RCPT TO.

Strict mode limitations are similar to those listed for the Web API above:

  • You cannot specify a "CC" header without a "To" header – this will result in a sending error. The “To” header without “CC” is allowed.
  • The number of addresses in the "To" header is limited to ten; the same restriction applies to the "CC" header. There can also be a maximum of ten blind copies.
  • If the address from the email parameter is not listed as either “To” or “CC” (i.e., it is used to create a blind copy), then this address can only be on your own domain already verified in UniOne. You cannot send blind copies to domains other than those you own. Unfortunately, we have to enforce this rule to prevent email phishing.

 

In the world of email marketing, the delivery of messages via email is one of the key aspects. However, even the highest-quality mailing list can encounter delivery problems if it contains unreachable email addresses. In this article, we’ll see how email address validation can improve the effectiveness of your email campaigns and take a look at UniOne’s validation methods and proper ways to use this functionality.

What is email validation

Email address validation is the process of checking email addresses for correct syntax and functionality. The purpose of this process is to get rid of addresses that are either invalid or could negatively impact the sender's reputation. Through validation, you can ensure that recipients' addresses actually exist and are capable of receiving messages.

Why validation is necessary

Maintaining a high level of deliverability enhances the sender's domain reputation. This, in turn, significantly reduces the likelihood of your emails ending up in spam or being blocked. Additionally, in mailing services, pricing is usually based on the number of emails sent – by sending messages to invalid addresses, you are just wasting your money.

When should you use email validation

If your subscription forms use single opt-in, i.e., subscription without confirmation, you’ll inevitably get a certain number of invalid email addresses. A user may make a typo, enter a one-time disposable address or even someone else's email. To avoid such cases, it's better to use a double opt-in procedure with confirmation. If, for some reason, this is not possible, consider integrating the email validation process into the registration form of your website. This way, you’ll be able to instantly inform users that the address they entered is invalid or unreachable.

Another common scenario is when a mailing list has not been used for mailing for a long time. Address owners may have deleted their mail or forgotten about you. Such a base needs to be checked for relevance, otherwise mailing services may block you due to a large number of returns, unsubscribes, and spam complaints.

Contact collection at offline events or through paper surveys may also lead to problems due to customer errors in addresses, illegible handwriting, or poor data collection organization. In this case, validation will also be extremely useful.

How address validation works

In response to the email-validation/single method call, you will receive: the status of the checked address; the reason it was set; the probability of using the address for mailings; and several other fields with useful information. You can read more about this in our documentation.

Since the email-validation/single method is intended for single checks, it has certain limitations. A maximum of two simultaneous requests are allowed, and if exceeded, an error will be returned. The check must be quick, so we limit the checking time: if a recipient’s mail server does not respond in 5 seconds, the validation result may be undefined.

Email address validation is an important way to improve deliverability and enhance the sender's reputation. By using UniOne’s validation, you can ensure the high efficiency of your email campaigns.

 

Projects offer you a way to completely isolate data for different independent domains, unreachable address lists, templates, mailing settings etc.

Let’s consider a few possible scenarios for projects:

  • You offer UniOne-based email marketing services to different clients or use UniOne as a white label solution as part of your infrastructure. To keep your clients’ data separate from one another, you may create a separate project for each client.
  • You have multiple departments, each one with its own web sites and mailing lists, and your employees should be able to access only the data that is related to their department’s resources. A practical solution would include creating a separate project for each department and using Shared access to manage individual access rights.
  • You send email campaigns across markets in different countries, each with its dedicated sender domains, dedicated IPs and other custom settings. Again, projects would be an ideal solution in this case.

While keeping your projects entirely isolated, you may still manage them and make payments using your primary UniOne account. This would allow you to use the most cost effective tariff, based on the combined volume of emails across all of your projects.

Each project has its own API key, and API calls with a particular key will affect only data related to that project. This way you may be sure that the projects are entirely independent: for instance, if an addressee unsubscribes from any of your projects, it will not affect their subscription to the other ones.

You may manage your projects and create new ones either via Settings/Projects page in your account or by using project-related API calls. By default, access to this page and methods is disabled for security reasons. To enable projects functionality, please contact our support team.

While setting up your projects, keep in mind the following:

  • For maximum project independence, a sender domain is verified and enabled separately for the main account and for any of the projects using it. If you’d like to let all your projects use verified domains from your main account, please send a request to our support team.
  • You can limit users’ (your clients or employees) access to statistics, templates and other data by specifying a list of projects available to them. This is done by selecting the projects you need in the Shared access  menu.

What are suppression lists and what are they used for

Suppression lists, or lists of unreachable addresses, serve as a means of maintaining your sender reputation and nurturing your subscribers. By using them, you suppress messages to certain addresses which, if sent, would be likely to do you harm. Our service will automatically filter out the email addresses found in these lists.

An email address may be suppressed for a variety of reasons. It may be syntactically invalid; the mailbox owner may unsubscribe from your mailings or issue a complaint; or the receiving server may be known to block certain types of emails it deems unwanted.

How does an email address become suppressed

Generally, there are three entities that may be the source of information used to render an address as suppressed:

  • The system: an address may be considered unreachable when a large number of delivery attempts fail. Other possible reasons include the address being registered as a spam trap.
  • The owner: your subscriber may cancel their subscription or issue a complaint.
  • The client: you may opt to add an address to a list with an appropriate status – unsubscribed, complainer, etc.

The particular source is returned as a value of the source field when calling the suppression/get API method. This method also provides the related cause – user complaint, unsubscription, delivery issues, etc.

Types of suppression lists in UniOne

There are two types of suppression lists in UniOne:

  1. The global suppression list – addresses that are considered unreachable for all users. The only sources here are the system and the address owner, but never any of our clients.
  2. The local suppression list contains addresses that are suppressed for your mailings only, based on previous sending attempts or the owner’s actions.

The global suppression list is a major benefit as it suppresses any mailings to addresses that are already known to be unreachable and thus helps you maintain a good deliverability score and solid sender reputation.

How suppression lists improve your deliverability

Let’s consider the following three scenarios.

Sending out marketing emails

Mass marketing emails are more likely to be considered as spam by mailbox providers, thus the primary goal is to avoid sending emails to unreachable addresses and keep the number of complaints to a minimum. It makes perfect sense to use our prior knowledge about the addresses that cannot be reached or whose owners tend to place complaints. As such, both local and global suppression lists are used for this type of email, which helps you achieve a good sender reputation and keep the number of complaints to a minimum, which in turn will improve your deliverability rate.

The default parameters for the email/send API method are optimized for this type of email.

Sending regular transactional messages

Abandoned cart emails, balance notifications, billing reminders and the like are anticipated by the recipient, so complaints are far less likely. In this case, it would be reasonable to turn off the global suppression list and use only the local one.

To use this scenario, set the bypass_global parameter value to 1 when calling the email/send

Sending high priority transactional messages

This category includes emails that need to be delivered even at the risk of degrading your sender reputation, e. g. account confirmations, password resets or security notifications. It would make sense to skip checks for both the global and local suppression lists. However, it is advised to consider possible cases where the local list needs to be used partially, for example, to suppress letters to known complainers.

In order to send high priority letters to addresses known to be unreachable, specify bypass_global=1 and bypass_unavailable=1. If you also need to contact unsubscribed addresses, add bypass_unsubscribed=1. Similarly, with bypass_complained=1 emails will be sent to complainers as well.

Managing suppression lists

To view, add or remove addresses from suppression lists, our Web API offers a set of suppression methods. For individual addresses, you may also use the Tools/Email search page in your account.<

You may remove addresses from your local suppression list whenever you like, however removal from global lists is limited to a few addresses per day and may not be available for certain addresses.

If you implement your own unsubscribing mechanism, we strongly recommend adding unsubscribed addresses to the UniOne suppression list as well, using suppression/set API method – this will help us to ensure that no emails are sent to anyone who has canceled their subscription. This is especially useful if your messages originate from several sources, and lists of unsubscribed addresses for different types of mailings are maintained separately.

While viewing statistics, setting up webhooks, and processing delivery results you will encounter various email delivery statuses. This article provides a detailed specification of such statuses and how they should be processed.

Standard statuses

At the most basic level, there are eight standard email statuses. These statuses are returned via webhooks or downloaded using the event-dump/* methods. The status field can have one of the following values:

  • sent — the email has been successfully checked and put in the queue for sending. At this stage we do not know yet whether it was delivered or not.
  • delivered — the email has been successfully accepted by the recipient’s mail server. Later this status may change to “opened”, “clicked”, “unsubscribed”, or “spam”.
  • opened — the email has been delivered and read by the recipient. The status may still change to “clicked”, “unsubscribed”, or “spam”. To enable read tracking, you must specify track_read=1 while sending.
  • clicked — the email has been delivered and read, and the recipient has clicked on one of the links in the message. The status may change to “unsubscribed” or “spam”. To enable click tracking, you must specify track_links=1 in the email/send parameters.
  • unsubscribed — the email has been delivered and read, and the recipient has opted to unsubscribe using the unsubscribe link included in the message or specified in the List-Unsubscribe email header. This status is final.
  • soft_bounced — a transient error has occurred while trying to deliver the message. UniOne will take additional delivery attempts for a period of 48 hours, starting from the first attempt. In case of success, the status will be changed to “delivered”, otherwise it will be “hard_bounced”.
  • hard_bounced - delivery attempts failed, there will be no further attempts to deliver the particular message. The status is final. This may occur due to different reasons; extended status information is provided in delivery_info.delivery_status, described below. The full SMTP server response is also available for analysis as delivery_info.destination_response value. A few common reasons are: the target address is not available; the message has been rejected as spam; the destination mailbox has no free space left.
  • spam — the message has been successfully delivered and manually marked as spam by the addressee. This status is final. The information is only available for domains supporting FBL technology, e.g. msn.com, outlook.com, hotmail.com, live.com, ukr.net, yahoo.com, aol.com.

Extended statuses

If you set the value of delivery_info to 1 while creating a webhook, an extended delivery status will be added to the event data. The extended status is also available in the CSV data obtained with event-dump/* methods. We use these extended statuses to provide detailed delivery information in the statistical reports

Extended statuses are determined by analyzing the SMTP server responses. Oftentimes the error code or even the full error message is not sufficient here, because different servers and mailbox providers tend to use them somewhat inconsistently. Also, as mailbox providers evolve, existing messages may take on different meanings and new ones may be added. Therefore we do not provide an exhaustive list of extended statuses, and we cannot guarantee that the list will not be changed in the future; however, the semantics of existing statuses will remain unchanged.

Extended statuses are not available for all events. If the value is missing, you are best advised to be guided by the standard statuses described above.

Below is a list of extended statuses, grouped by alleged system action.

Success

ok_sent

The message has been sent (an intermediate status before delivery or non-delivery).

ok_delivered

The message has been delivered.

ok_read

The message has been delivered and opened by the recipient.

ok_link_visited

The message has been delivered and opened; the recipient has clicked on one of the link.

Complaint or unsubscription – the address is added to the list of complainers or unsubscribed addresses. The subsequent mailings to this address will be blocked, unless the address is removed from the blocking list using suppression/delete.

ok_spam_folder

The message has been delivered and placed into the Spam folder by the receiving server.

ok_fbl

The message has been delivered and manually tagged as Spam by the recipient.

ok_unsubscribed

The message has been delivered, and the addressee canceled the subscription using the unsubscribe link.

Temporary failure – a “soft bounce”, additional delivery attempts will be made.

err_will_retry

One or more delivery attempts were unsuccessful, the system will retry. The status is not final.

Non-existent – the receiving SMTP server says the address does not exist. UniOne blocks any attempts to send email to such addresses for a long period of time (6 months for most mailbox providers). After that the address will be reactivated, because the mailbox may eventually be restored or registered anew.

err_user_unknown

Address does not exist (and could never have existed).

err_user_inactive

A previously active address is no longer used, delivery has failed.

err_mailbox_discarded

The mailbox has been deleted.

Rejected as spam – the receiving SMTP server has clearly stated that the message will be rejected as spam. This does not always imply that the next message from the same sender will be also declined.

err_spam_rejected

The message has been rejected as spam.

err_spam_skipped

The message was not sent because other messages from the same task were previously rejected by the recipient’s server as spam.

err_spam_removed

The message was not sent because other messages from the same task were previously rejected by the recipient’s server as spam (same as previous, but at later stages of mailing).

Long-term unreachable – numerous failed attempts in the past have led to the address being tagged as unreachable for a long period of time (6 months for most mailbox providers). Emails to such addresses are blocked by the system.

err_unreachable

Address tagged as unreachable due to multiple delivery errors.

skip_dup_unreachable

Sending canceled because the address has been previously tagged as unreachable.

Short-term unreachable – delivery attempts failed, but the address will be tagged as unreachable for a few days only, or will be immediately available for further mailing. 

err_mailbox_full

Mailbox is full.

skip_dup_mailbox_full

Sending canceled because recent attempts resulted in “mailbox full” response.

err_too_large

The receiving server says the message is too large.

err_unsubscribed

The addressee has unsubscribed from your messages.

err_blacklisted

The message has been rejected because the sender domain or IP was found on a blacklist.

err_skip_letter

Sending canceled because the target address is temporarily unreachable.

err_domain_inactive

The target domain does not exist or does not accept mail.

err_destination_misconfigured

The target domain does not accept mail due to a solvable issue (e.g. SMTP service temporarily down).

skip_dup_temp_unreachable

Sending canceled because the target address is temporarily unreachable.

err_lost

The email has not been sent due to the inconsistency of its structure, or has been lost as a result of an internal error. The user should re-send the letter.

err_internal

An internal error has occurred. The user should re-send the letter.

err_delivery_failed

Delivery failed due to unspecified reasons.

 

Reasons to block sending

In certain cases, UniOne does not allow a particular email to be sent (for example, an addressee has unsubscribed from your messages). The email/send call will return the reason for blocking. The reason may also be obtained using the API methods for suppressed addresses, suppression/get and suppression/list.

A reason for blocking is not the same thing as a delivery status, but as they are logically interconnected, we find it convenient to give a description here.

The reasons for blocking may be as follows:

unsubscribed

The addressee has unsubscribed by following the link in the email body or List-Unsubscribe header, or was added to the list with suppression/set API call.

temporary_unavailable

One or more previous attempts for this address were unsuccessful, and the address has been tagged as “temporarily unavailable”. In a few days, the status will be removed and the address will be made available for further mailings. The reasons for this (e.g. mailbox is full or a spam block is in effect) are described above in the extended statuses table.

permanent_unavailable

Address is permanently unavailable, as verified by multiple sending attempts. Strictly speaking, the status is not quite “permanent”, usually it is in effect for about half a year.

complained

The addressee has tagged one of the previous letters as spam, issued a complaint in some other form or added to the list using suppression/set API call.

blocked

The address is blocked by the system. There is a small number of such addresses; most of them are either spam traps or addresses like support@gmail.com which definitely does not belong to a person.

invalid

The target address is invalid (for example, the @ sign is missing).

duplicate

The address has been included in the same email/send call more than once.

To register subscribers’ clicks, all links in your emails are replaced with links to a dedicated link tracking domain. When a link is clicked, the click is registered, and then the reader is redirected to an original target page. UniOne allows you to use your own domains for link tracking, which increases the credibility of your messages as unfamiliar domain names do not show up in the email.

 

How to add your own tracking domain

To add a new domain, go to the Settings – Tracking domains page and click the plus icon alongside the page title.

The domain name you enter will be used for link tracking. We recommend using a third level domain, preferably a subdomain of your brand’s primary domain. For instance, for example.com you may use names like send.example.com or link.example.com. If you use projects, you’ll also be able to specify projects for this domain. When ready, click “Save”.

The domain’s status will be “Awaiting DNS setup”, and you’ll need to add a few DNS records for your domain (this is done in your domain’s registrar control panel). To view and copy the required records, click the gear icon.

After the records are added, you’ll need to wait until they propagate and are updated in our system. The time it takes varies from a few minutes to a couple of hours, depending on your provider’s settings. If everything’s ok, the domain status will change to “Setup in progress”.

In the following 48 hours, our specialists will perform the required system setup, and the status will change to “Ready”. The domain may now be activated and, if necessary, set as default by clicking the star icon. If you’ve set up multiple tracking domains, specify the “custom_backend_id” value in email/send API call to use a particular one.

If the status changes to “Error”, contact our support team to find out what’s wrong and be advised on possible fixes.

To delete a domain you no longer need, click the cross-out icon on the right. If the domain was previously set as default, a system domain will be used instead.

 

General information

Dedicated IP addresses allow you to build your own reputation scores for your campaigns, totally independent from other clients who use our common pool of IPs. This strategy offers substantial deliverability benefits; on the other hand, it also requires some time to implement, since your new IPs must be “warmed up” before full-scale usage, in order to minimize the risks of blocking or ending up in spam. Mailbox providers are suspicious about large volumes of emails coming from new IPs or domains, so the number of messages sent from a new address should be increased gradually. This procedure is called “IP warmup”.

Initial setup

  1. First of all, you will need to calculate the number of IPs you’ll need, based on your current infrastructure and sending volumes. Prepare a list of sending domains which you want to use with dedicated IPs. If you need to use separate IP addresses for different domains, please make sure that you’ve created special projects for each of these domains.

  2. The required number of IPs for each domain or project is defined by the number of messages you’re intending to send. Currently we guarantee no less than 70 000 messages per hour from each fully warmed-up IP (the amount may actually vary from 70K to 100K, depending on the overall load and distribution of target domains). You can use this general formula for a quick estimate of the number of IPs you’ll need:
    number_of_IPs = emails_per_day / 85000, rounded upwards
    So, to send out, say, 10 million emails per month, or 333 000 messages per day you’ll need four dedicated IPs (333 000 / 85 000 = 3.9).
    * Based on the contents of your campaigns, our specialists may advise you to order one or more extra IPs, in order to mitigate any delivery issues. Our anti-spam service is constantly keeping track of deliverability issues for all our users’ campaigns and will provide additional data on the number of IPs needed with regard to most recent anti-spam trends and any particulars of your individual case.

  3. Open the Settings – Dedicated IPs page in your account and click the plus icon. 

     

     

    Enter a third level domain name which will serve as an IP pool name and tracking domain (for example.com, it may be something like send.example.org). Specify the number of IPs you need and click Save.

  4. After saving, our account will be charged for the amount of $20 for each dedicated IP (a one-time setup fee) plus IP rent according to the formula: $40 divided by 30 and multiplied by the number of days left in the current accounting period. Afterwards, the monthly service fee for your dedicated IPs will be charged together with your regular payment.

    (For custom contracts, the payment is carried out according to the contract’s terms.)

  5. On the Settings – Dedicated IPs page, click the gear icon alongside your domain name. You’ll see a few DNS records that you will need to add in your domain registrar’s management console. Initially the domain status will be “Awaiting DNS setup”.

  6. As soon as the new records are updated in our system (it usually takes up to two hours, depending on your provider’s settings), the domain status will change to “Domain setup in progress”.

  7. During the next 48 hours our specialists will perform the necessary setup, and the status will change to “Active”. Now your domain is ready for use, you may activate it and designate it as a default domain. If you’ve set up more than one domain and need to specify the one to be used while sending a particular letter, specify the corresponding custom_backend_id value while calling email/send. The values can be found on the same page, in the Backend ID column.

  8. If they do not show up after two days, please ask our support to check the issue. Our specialists will find out what has gone wrong and offer possible remedies. If any additional corrections for your DNS records are needed, we return to step 5.

  9. As soon as the DNS records are in effect, the warm-up procedure is initiated automatically. It usually takes 40 days, during which the system will automatically adjust the mailing volumes on a per-hour and per-domain basis. This minimizes the risks of spam blocking, allowing you to gradually build up a solid reputation for an IP.
  10. Consistency, gradualness and regularity are vital for a proper warmup, so the mailings need to be done in smaller chunks. As a result, large campaigns may be partially delayed. Generally, there are two ways to deal with such tasks:

    • The default “hard limit” scheme suggests that our system allocates as many emails as can be sent from new IPs during a 10-hour period. Any daily emails over this quota will be sent via the common IP address pool. This sequence guarantees proper IP warmup and queue management. However, the maximum queueing delay with this scheme will be 10 hours.
    • The “soft limit” scheme, available upon request, requires instant redistribution of emails between dedicated and common IPs. With smaller email quantities or irregular flows, dedicated IPs may not be properly warmed up, as the common IP pool provides substantially higher throughput. This is why we recommend this scheme only if you can provide a steady flow of emails with regard to the hourly limits table, shown below.

      During the IP warmup period, it is highly recommended that you send the required number of emails each day.

  11. IP warmup is carried out automatically following a proven procedure. Our anti-spam team members will monitor delivery rates for every IP and advise you on quota adjustments to get the best results.

    Warmup limits table

    The approximate hourly limits for Gmail and Yahoo Mail are shown in the table below for reference. The exact quotas, aimed at minimizing the possibility of spam blocks, vary depending on mailbox provider, the day of the warm up sequence and many other factors.

    Day of warmup Google, emails per hour Yahoo, emails per hour
    1 48 48
    2 57 57
    8 225 225
    15 1100 1000
    23 12000 2500
    28 47000 5000
    35 unlimited 10000
    40 unlimited unlimited
  12. To learn what your current exact quotas are, feel free to contact our tech support anytime. As soon as the warmup procedure is over (typically in 40 days), all limits are removed, and your IPs will be used for all of your mailings.

 

We wish you all the best using UniOne, and may all your emails reach the designated inboxes!

UniOne offers great collaboration features for your email marketing. You can let your designer manage templates, provide marketers with statistics, and give network admins access to domain settings.

Types of access

Several types of access are already defined: administrator, developer, tech support, marketer, accountant, designer, client and customized. Let’s take a closer look at each of them.

Administrator

Maximum access rights. This role has control over every available setting, except the primary email address and password.

Developer

Similar to Administrator, but some settings are read-only, such as account details, payment settings and tariff.

Marketer

This role grants access to all pages under Tools and Statistics menus. This means a user will be able to work with templates, assess deliverability rates, download event data in CSV (including email addresses), examine delivery problems and manage address statuses.

Tech support

The Support role has the exact same rights as the Marketer described above, and can also access Settings in read-only mode (the API key will not be displayed).

Accountant

This role has full access to tariff, balance, and payment history information, and can also change the tariff plan. The Accountant can view statistical data, but CSV download is not available.

Designer

The only option available for Designer is to view and edit templates in your account.

Client

This role grants access to Statistics only, including the ability to download data.

Customized

If for some reason none of the roles described above fits your particular needs, you may set custom access permissions by checking the options you want to grant.

How to set up shared access

Click the menu button, navigate to Settings – Shares Access and invite a new collaborator by clicking the plus sign.

In the dialog box you should specify the new workgroup member’s email address, and set the allowed rights. If the Readonly box is checked, they will be able to view the data without making any modifications.

After clicking OK, the person will receive a confirmation email. If your addressee does not have a UniOne account yet, they will be prompted to create one.

By clicking the confirmation link (and completing the sign-in process, if necessary) the person will receive the capacity to switch to your account by clicking the corresponding option in the top left corner.

Your colleagues will see only those menu items you’ve granted them access to.

Modifying and disabling a share

To add, modify or revoke previously given rights, you click on the pencil icon for the corresponding share. By clicking the cross icon, you permanently delete the person from the list. If you want to restrict their rights only temporarily, simply uncheck all boxes – this way you won’t need to create the entry anew.

The two-factor authentication function will help to protect your account from intruders.

After logging in using email and password, the system will prompt you to enter a code from the Google Authenticator application installed on your mobile device (the code changes every 30 seconds). This way a hacker won't be able to log in just by stealing your password.

How to enable 2FA

  1. Visit the dedicated page for managing two-factor authentication (section "Account" -> "Security"), then click the "Configure" button:
    2fa settings page
  2. On your mobile device, add your UniOne account to the Google Authenticator app.

    Install the Google Authenticator app (iOS / Android) on your mobile device. In the application, click the "Add account" button (choose one of two options: scan a QR code or enter the digital code)

    If you have chosen "Scan QR-code" - point the camera at the code in the UniOne 2FA settings page.

    If you selected "Enter code" - enter the name of your account (e.g., "UniOne") and enter the code that is specified on the two-factor authentication settings page in the UniOne account.

    You have successfully added your UniOne account to the Google Authenticator app!

  3. Enter the six-digit code from the Google Authenticator app and click the "Enable" button:
    2fa setup screen

Two-factor authentication has been successfully enabled.

Make sure your mobile device time is set automatically. If the time of your device is set manually, the new access codes generated every 30 seconds may be out of sync and lead to an error when entering.

How to log in with 2FA enabled

Enter your email and password on the log in page.

Enter the six-digit code from the Google Authenticator app on your mobile device and click on the "Sign in" button.

How to recover your password with 2FA enabled

Enter your email and click on the "Recover password" button.

Open the Google Authenticator app on your mobile device to view the code.

Enter the six-digit code from the Google Authenticator application on your mobile device and click on the "Recover password" button once more.

How to disable 2FA

Go to the two-factor authentication management page.

Enter the six-digit code from the Google Authenticator app on your mobile device and click on the "Disable" button.

After doing this you will see a page without the enabled function and with the "Configure" button.

 

Important! If you do not have access to your mobile device with the Google Authenticator app installed, please contact support.

In this report, you can see data for messages that could not be delivered to the recipients, or about which there were complaints - for the last 32 days, today included:

non-delivery report screenshot

You can choose an arbitrary period within these 32 days. If the period is one day, then a detailed hourly breakdown of events for those 24 hours will be shown, if the period is more than a day, then the breakdown will be daily.

In this case, the “day” is defined by the UTC time zone.

You can filter events by selecting sender email address and / or recipient domain. Do not forget to click the "Apply" button after changing dates or sender/recipient filters to update the graph.

You can choose one of two data display modes:

All events - in this mode, each delivery failure event is counted and leads to an increase in the number of events of a defined failure type on the day that the event occurred (or per hour, if the statistics are broken down by hour). For example, a message which has been rejected as spam after 10 retries will be counted as sent 9 times and rejected as spam one time.

Unique events - this mode counts only events that are unique for a single message within a day (or an hour for an hourly breakdown). If during the day there were several repeated attempts to deliver the email, then only one retry will be counted. 

Events are divided into the following groups:

  • Retries. These are the so-called "soft bounces", i.e. replies from the recipient's server about the temporary impossibility of delivering the email. UniOne will make repeated attempts to deliver these emails over two days.
  • Unavailable. This group includes email addresses to which, according to UniOne’s information, delivery is impossible or prohibited. These can be addresses, messages to which have been repeatedly rejected by the recipient's server for a long time. Either the owners of the addresses have previously complained about the emails or have asked to add them to a permanent block list. Some of these statuses can be reset using the Email Search tool.
  • Non-existent. The recipient server replied that the address does not exist or is inactive. This is a "hard bounce", i.e. permanent error, with such an error it is pointless to try to send the same email again.
  • Rejected as spam. There were one or more delivery attempts, but the recipient's server rejected the letter explaining that it considers it to be spam. Also a "hard bounce".
  • Other non delivery. The email was rejected for reasons other than “rejected as spam” or “address does not exist,” or the reason could not be reliably identified. This is also a "hard bounce".

Statistics for the current day may be a little late as it takes some time to process and index the data. Usually, this delay will not exceed an hour.

If you are using projects, then in the upper left corner of the screen you can switch to viewing statistics for a single project, for the main project (main account), or select “all projects” to view summary statistics for all projects at once.

In this report, you can see the data on the delivery events of your email messages for the last 32 days, today included:

delivery report screenshot

You can choose any particular period within these 32 days. If that period is one day, then a detailed hourly breakdown of events for those 24 hours will be shown, if the period is more than a day, then the breakdown will be daily.

In this case, the definition of any day is determined by the UTC time zone.

You can filter events by selecting sender email address and / or recipient domain. Do not forget to click the "Apply" button after changing dates or sender/recipient filters to update the graph.

You can choose one of two data display modes:

  • All events - in this mode, each event is counted and leads to an increase in the number of events of a defined type on the day that the event occurred (or per hour, if the statistics are broken down by hour). For example, an email sent and delivered after a third retry, and then read twice, will count as a send, delivery, three retries, and two read events.
  • Unique events - this mode counts only events that are unique for a single message within a day (or an hour for an hourly breakdown). For example, an email sent and read twice yesterday and read three times today will count as one sending, delivering, and reading yesterday and one reading for today - with a daily breakdown. 

Events are divided into the following groups:

  • Sent. The first attempt to send an email to the recipient's SMTP server is counted. Retries, if any, are not counted. But temporary errors (soft bounces) that lead to retries are counted in the Failures group.
  • Delivered. If the recipient's server has accepted the message, then this event is counted in the “Delivered” group. Unfortunately, this does not guarantee that it will reach the inbox - despite the confirmation of delivery, the recipient's server may delay the message for some time to study it or even send it to the "Spam" folder.
  • Opened. The fact of an email being read is tracked by viewing a small one-pixel image at the end of the email. This does not always work exactly - some mail services or programs may block this type of tracking. But in general, the tendency to increase or decrease interest in your emails allows you to control the process. Read/open tracking is possible only if the email/send API method track_read = 1 parameter was used when sending.
  • Clicked. These are clicks on any of the links from the email, with the exception of unsubscribe links. Click tracking is only possible if the email/send API method track_links = 1 parameter was used when sending.
  • Unsubscribed. Only unsubscriptions made via the UniOne unsubscribe link or unsubscribe block are counted, as well as the List-Unsubscribe header generated by UniOne. You can read more about unsubscribe links here.
  • Complained. This category includes email addresses whose owners have clicked the "this is spam" button which UniOne discovered by using FBL technology.
  • Bounced. Temporary delivery errors (soft bounces) and permanent delivery errors (hard bounces) fall into this category. A breakdown of nondelivery by reason can be seen in the non delivery report

Statistics for the current day may be a little late, as it takes some time to process and index the data. As a rule, the delay will not exceed an hour.

If you are using projects, then in the upper left corner of the screen you can switch to view statistics for a single project, for the main project (main account), or select “all projects” to view summary statistics for all your projects at once.

In UniOne, statistics can be obtained in several different ways:

Statistics section

If you need detailed visual statistics, then open "Statistics" menu section in UniOne control panel.

In the delivery report, you can see the success of your mailing for the last month broken down into different sections - taking into account the sending address and the delivery domain, with daily or hourly details, the absolute number of all events or only unique reads / transitions.

In the non-delivery report, you can study the reasons for any non-deliveries in the last month to understand how to fix the situation. Here, too, there is the possibility of filtering by sending address or domain, there is also a daily or hourly detailing. And don't forget that UniOne also provides you with the ability to view last week's SMTP error messages directly from the recipient servers for each individual email on the Delivery Issues page.

Dashboard

When you log in, you will see the latest deliverability summary on the home page. It is simple, in comparison with the statistics section - the data is shown only for the last week and without the possibility of filtering. But on the other hand, it is updated in real time, in contrast to the more functional, but slightly lagging statistics section.

Event-dump methods

A set of API methods used to obtain a list of events for a given time period in CSV format. Data is stored for up to 45 days, depending on your tariff. This means that you can request data starting from 00:00:00 45 days ago and up to the current time. For high volume senders, the period defaults to 7 days and may be extended upon request. You can limit the report to certain recipient and sender addresses, campaign IDs, etc. using filters.

Webhook API

If you need both real-time and the most detailed information at the same time, then you can connect through the Webhook API notifications about all events that occur with each email you send. This includes e.g. the links clicked, information about the user's browser or responses from SMTP servers. To do this, you will need to program a notification handler, but with detailed documentation this is not so difficult, and we recommend this method to you if you are looking to develop a serious solution. Benefits include:

  • Unlimited storage time - you decide how much to keep.
  • Any analytical slices are based on the most complete raw data - load them into your favourite analytical system and process them as you want.
  • Data in real time - you can build on them your own trigger system of reactions to the actions of your users.

Working with the transactional emails service UniOne you may encounter instances of the system blocking the delivery of your emails, causing them to not reach their destination.

According to the company's anti-spam policy, UniOne provides automatic spam blocking. Perhaps sending from your account to some domains has been blocked.

General principles of spam blocking


  1. If user’s emails, sent from one UniOne server (SMTP), are rejected as spam by the recipient's server (eg, gmail, hotmail.com, etc.) for 10 times, the system will block the sending of messages from the current SMTP server, and then continue sending using other servers.
  2. If 5 UniOne servers are blocked for the particular domain, the system restricts sending to this domain and will no longer try to send emails to the recipients from this domain.

More information about spam blocking


Information about outgoing UniOne SMTP servers and recipient domains blocking can be obtained by a webhook (setting event “spam_block” : [“*”]).

The information will be returned as follows:

 { 
            "event_name":"transactional_spam_block",
            "event_data":
            { 
              "block_time":"YYYY-MM-DD HH:MM:SS",
              "block_type":"one_smtp",
              "domain":"domain_name",
              "SMTP_blocks_count":8,
              "domain_status":"blocked"
             }
}

where:

block_time - outgoing SMTP blocking time (UTC)

block_type - can return one_smtp (if a single SMTP was blocked), all_smtp (if all SMTPs were blocked for the recipient’s domain)

domain - recipient’s domain name

SMTP_blocks_count - counter that shows the quantity of the blocked SMTP

domain_status - can return blocked or unblocked (shows whether the current domain is allowed to send to)


If you have a problem with sending to a particular domain and this domain is restricted but you are sure that the content you are sending is acceptable (not spam), feel free to contact the support to solve your problem.

Visual editor allows you to create an email which will look equally attractive on your laptop, mobile or tablet.

An email is comprised of horizontal rows, which in turn may contain one or more diverse blocks: texts, images, buttons, or videos. By default a new email consists of one row containing one block. You can add more rows with the necessary number of blocks by switching to the ROWS tab and dragging the appropriate preset row onto your email.


Next, you add the required content to each block by switching to the CONTENT tab and dragging the necessary content type onto the related block.

Adding blocks


 Each row can be deleted or duplicated at need. When you left click any unused area inside the row, a small menu pops up on the right containing a trash icon (click to delete the row) and a double-square icon (click to duplicate the row). A four-arrow handle also appears on the left, allowing you to relocate the row.

Duplicating and deleting rows

When a row is selected, the ROWS tab shows a number of properties for this row. You may adjust the number of columns, change background colors and more.


If you click any block instead, the same icons and handle will apply to this block only.

Deleting and duplicating content blocks


If you click the Revert button in the lower right corner of the editor, you will cancel your most recent action. A click on the timer icon shows the entire editing history.

History

When you are satisfied with the result, click the “Continue” button in the upper right corner. The editor will close and you will see the result in preview mode. IMPORTANT NOTICE: the template is not yet saved, as other properties might have been changed. To save the entire template, including your design changes, you must then click the "Save" button.

 

1. Create an email template.


First, create the email body without substitutions in order to have an idea of the final design of the letter in the recipient's inbox.

2. Create the substitution structure


The substitutions can be set in the parameters substitutions and global_substitutions of email/send, or in the parameter global_substitutions of template/set. The substitutions can be used in the following parameters:

  • body.html
  • body.plaintext
  • body.amp
  • subject
  • headers
  • options.unsubscribe_url
  • from_name

3. Create email/send request


Replace the changing content in body and other parameters (see above the parameters in which it is possible to use substitutions) by the substitutions using use cases. Add the substitutions structure and other parameters according to the method documentation.

Example of Velocity powered email

View HTML email body with substitutions. The result is as follows:

 

Request body, email/send:

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{
  "api_key": "KEY",
  "message":
  {
    "template_engine" : "velocity",
    "body":
    {
      "html": "<!DOCTYPE html PUBLIC \"-//W3C//DTD XHTML 1.0 Transitional//EN\" \"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd\"><html xmlns=\"http://www.w3.org/1999/xhtml\"> <head> <meta http-equiv=\"Content-Type\" content=\"text/html; charset=utf-8\"/> <title>Untitled Document</title> </head><body> <table width=\"600\" border=\"0\" align=\"center\" cellpadding=\"0\" cellspacing=\"0\"> <tr> <td style=\"text-align:right; vertical-align:middle;\"> <span style=\"color:#999999; font-size:11px; font-family:Arial, Helvetica, sans-serif; line-height:normal;\">Your promo code: $trigger.promocode</span> </td></tr><tr> <td height=\"10\" style=\"line-height:10px; height:10px;\">&nbsp;</td></tr><tr> <td height=\"10\" style=\"border-bottom:#047DFF 3px solid; line-height:10px; height:10px;\">&nbsp;</td></tr><tr> <td height=\"20\" style=\"border-left:#bbbbbb 1px solid; border-right:#bbbbbb 1px solid;\">&nbsp;</td></tr><tr> <td style=\"border-left:#bbbbbb 1px solid; border-right:#bbbbbb 1px solid; padding:0 30px 0 30px;\"> <span style=\"font-family:Arial, Helvetica, sans-serif; color:#333333; font-size:17px;\">Hello<a href=\"#\" style=\"color:#3e77aa; text-decoration:none;\"> $user.name.</a></span> </td></tr><tr> <td height=\"20\" style=\"border-left:#bbbbbb 1px solid; border-right:#bbbbbb 1px solid;\">&nbsp;</td></tr><tr> <td style=\"border-left:#bbbbbb 1px solid; border-right:#bbbbbb 1px solid; padding:0 30px 0 30px;text-align: left\"> <span style=\"font-family:Arial, Helvetica, sans-serif; color:#333333;font-weight:bold; font-size:24px; line-height:normal;\">We Have Recommendations For You </span> </td></tr><tr> <td height=\"20\" style=\"border-left:#bbbbbb 1px solid; border-right:#bbbbbb 1px solid;\">&nbsp;</td></tr><tr> <td style=\"border-left:#bbbbbb 1px solid; border-right:#bbbbbb 1px solid; padding:0 30px 0 30px;\"> <p style=\"font-family:Arial, Helvetica, sans-serif; color:#333333; font-size:17px; line-height:normal;\">You have been looking for a $lookingfor.deviceType with $lookingfor.screenResolution display, $lookingfor.ppi ppi, $lookingfor.ram RAM. </p><p style=\"font-family:Arial, Helvetica, sans-serif; color:#333333; font-size:17px; line-height:normal;\">Want to have a cosultation? Easy! Our managers will help you to make the right choice by phone: $trigger.deliverytelephone. </p></td></tr><tr> <td height=\"20\" style=\"border-left:#bbbbbb 1px solid; border-right:#bbbbbb 1px solid;\">&nbsp;</td></tr><tr> <td style=\"border-left:#bbbbbb 1px solid; border-right:#bbbbbb 1px solid;\"> <table width=\"100%\" border=\"0\" cellspacing=\"0\" cellpadding=\"0\"> <tr> <td width=\"30\">&nbsp;</td><td style=\"text-align:left; vertical-align:middle;\"><span style=\"font-family:Arial, Helvetica, sans-serif; color:#333333; font-size:17px; line-height:normal; \">Your $trigger.discount promo code: <span style=\"font-family:Arial, Helvetica, sans-serif; color:#ee1212; font-size:25px;\">$trigger.promocode</span></span></td><td width=\"30\">&nbsp;</td></tr><tr> <td width=\"30\">&nbsp;</td><td style=\"text-align:left; vertical-align:middle;\"><span style=\"font-family:Arial, Helvetica, sans-serif; color:#333333; font-size:12px; line-height:normal; \">The discount is valid till $dateFormat.format('full_date', $date_exptime)</td><td width=\"30\">&nbsp;</td></tr></table> </td></tr><tr> <td style=\"border-left:#bbbbbb 1px solid; border-right:#bbbbbb 1px solid; height:35px\">&nbsp;</td></tr><tr> <td style=\"border-left:#bbbbbb 1px solid; border-right:#bbbbbb 1px solid;\"> <table border=\"0\" cellpadding=\"0\" cellspacing=\"0\" style=\"width: 648px;\"> <tbody> <tr> <td width=\"200\">&nbsp;</td><td><div style=\"text-align: center; vertical-align: middle; -webkit-border-radius: 5px; -moz-border-radius: 5px; border-radius: 5px; background-color:#047DFF; border-bottom: #047DFF 5px solid;\"><span style=\"color:#cccccc\"><a href=\"#\" style=\"color: #ffffff; font-size: 28px; text-decoration: none; font-family: Arial, Helvetica, sans-serif; line-height:50px;\" target=\"_blank\">Find More!</a></span></div></td><td width=\"200\"></td></tr></tbody> </table> </td></tr><tr> <td height=\"20\" style=\"border-left:#bbbbbb 1px solid; border-right:#bbbbbb 1px solid;\">&nbsp;</td></tr><tr> <td style=\"border-left:#bbbbbb 1px solid; border-right:#bbbbbb 1px solid;\"> <table width=\"648\" border=\"0\" cellspacing=\"0\" cellpadding=\"0\"> <tr> <td width=\"30\">&nbsp;</td><td align=\"left\" valign=\"top\" style=\"text-align:left; vertical-align:top;\"> <table width=\"100%\" border=\"0\" cellpadding=\"0\" cellspacing=\"0\"> <tr> <td style=\"border-bottom:#eaeaea 1px solid\"> <table width=\"100%\" border=\"0\" cellspacing=\"0\" cellpadding=\"5\"> </table> </td></tr>#foreach( $product in $products ) <tr> <td style=\"border-bottom:#eaeaea 1px dashed; padding-bottom:10px; padding-top:10px;\"> <table width=\"100%\" border=\"0\" cellspacing=\"0\" cellpadding=\"5\"> <tr> <td width=\"130\" rowspan=\"2\"><a href=\"$product.url\"><img src=\"$product.imgUrl\" width=\"130\"/></a></td><td width=\"330\" height=\"15\"><span style=\"font-family:Arial, Helvetica, sans-serif; color:#333333; font-size:15px;\"><a href=\"$product.url\" target=\"_blank\" style=\"color:#3e77aa; text-decoration:none;\">$product.title</a></span></td><td rowspan=\"2\" align=\"center\"><span style=\"font-family:Arial, Helvetica, sans-serif; color:#3e77aa; font-size:17px;\">$product.price</span></td></tr><tr> <td width=\"330\" valign=\"top\"><span style=\"font-family:Arial, Helvetica, sans-serif; color:#333333; font-size:12px;\">$product.description</span></td></tr></table> </td></tr>#end <tr> <td style=\"border-bottom:#eaeaea 1px solid; padding-bottom:10px; padding-top:10px;\"> <table width=\"100%\" border=\"0\" cellspacing=\"0\" cellpadding=\"5\"> </table> </td></tr></table> </td><td width=\"30\" align=\"center\" valign=\"top\" style=\"text-align:center; vertical-align:top;\">&nbsp;</td></tr></table> </td></tr><tr> <td height=\"20\" style=\"border-left:#bbbbbb 1px solid; border-right:#bbbbbb 1px solid;\">&nbsp;</td></tr><tr> <td height=\"20\" style=\"border-left:#bbbbbb 1px solid; border-right:#bbbbbb 1px solid; border-top:#bbbbbb 1px solid; height:20px; line-height:20px;\">&nbsp; </td></tr><tr> <td style=\"vertical-align:top;border-bottom: 3px solid #047DFF; border-left:#bbbbbb 1px solid; border-right:#bbbbbb 1px solid; font-family:Gotham, 'Helvetica Neue', Helvetica, Arial, sans-serif; text-align:left\"> <table cellpadding=\"0\" cellspacing=\"0\" style=\"border:0;border-collapse:collapse;width:100%\"> <tbody> <tr> <td width=\"50\">&nbsp;</td><td style=\"vertical-align:middle;height:29px\"> <a href=\"#\" target=\"_blank\" style=\"color:#3e77aa;text-decoration:none\"> <img src=\"http://unisenderfiles.storage.unisender.com/KBpictures/UniOne/smart.png\" alt=\"Телефоны, MP3\" title=\"Телефоны, MP3\" width=\"23\" height=\"23\" style=\"border:0;vertical-align:bottom;\">&nbsp;Smartphones, Tablets </a> </td><td style=\"vertical-align:middle;height:29px\"> <a href=\"#\" target=\"_blank\" style=\"color:#3e77aa;text-decoration:none\"> <img src=\"http://unisenderfiles.storage.unisender.com/KBpictures/UniOne/lap.jpg\" alt=\"Ноутбуки, планшеты и ПК\" title=\"Ноутбуки, планшеты и ПК\" width=\"23\" height=\"23\" style=\"border-width:0;vertical-align:bottom\">&nbsp;Laptops, PC </a> </td><td width=\"30\">&nbsp;</td></tr><tr> <td width=\"50\">&nbsp;</td><td style=\"vertical-align:middle;height:29px\"> <a href=\"#\" target=\"_blank\" style=\"color:#3e77aa;text-decoration:none\"> <img src=\"http://unisenderfiles.storage.unisender.com/KBpictures/UniOne/tv.png\" alt=\"Аудио, Видео, Фото\" title=\"ТВ, Аудио, Видео, Фото\" width=\"23\" height=\"23\" style=\"border-width:0;vertical-align:bottom\">&nbsp;TV, Audio, Video </a> </td><td style=\"vertical-align:middle;height:29px\"> <a href=\"#\" target=\"_blank\" style=\"color:#3e77aa;text-decoration:none\"> <img src=\"http://unisenderfiles.storage.unisender.com/KBpictures/UniOne/home.png\" alt=\"Бытовая техника и интерьер\" title=\"Бытовая техника и интерьер\" width=\"23\" height=\"23\" style=\"border-width:0;vertical-align:bottom\">&nbsp;Home, Garden, Tools </a> </td><td width=\"30\">&nbsp;</td></tr><tr> <td height=\"20\" width=\"50\">&nbsp;</td><td>&nbsp;</td><td>&nbsp;</td><td width=\"30\">&nbsp;</td></tr></tbody> </table> </td></tr><tr> <td height=\"10\" style=\"border-left:#bbbbbb 1px solid; border-right:#bbbbbb 1px solid; line-height:10px; height:10px;\">&nbsp;</td></tr><tr> <td style=\"border-left:#bbbbbb 1px solid; border-right:#bbbbbb 1px solid; \"> <table width=\"600\" border=\"0\" cellspacing=\"0\" cellpadding=\"0\"> <tr> <td width=\"600\" align=\"center\" valign=\"middle\" style=\"border-left:#CCC 1px solid; text-align:center; vertical-align:middle;\"><a href=\"#\" target=\"_blank\" style=\"color:#666666; font-size:12px; font-family:Arial, Helvetica, sans-serif; color:#3e77aa; line-height:normal;\">Unsubscribe</a> </td></tr></table> </td></tr><tr> <td height=\"20\" style=\"border-left:#bbbbbb 1px solid; border-right:#bbbbbb 1px solid; border-bottom:#bbbbbb 1px solid; height:20px;\">&nbsp; </td></tr></table> </body></html>"
    },
    "subject": "Recommendations",
    "from_email": "sender@mail.com",
    "from_name": "SENDER",
    "recipients": [
      {
        "email": "recipient@mail.com",
        "substitutions":
         
        {
          "date_exptime":"15/09/2017",
          "user":
          {
            "name":"John"
          },
          "trigger":
          {
            "promocode":"SUPERFREE1000",
            "deliverytelephone":"+1031341553356",
            "discount":"-5%"
          },
          "lookingfor":
          {
            "deviceType":"tablet",
            "screenResolution":"1920 X 1080",
            "ppi":"326",
            "ram":"2GB"
          },
          "products":
          
              {
                "title":"Amazon Tablet",
                "price":"50$",
                "description":"One of the best tablets for such a low price. Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmodtempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam,quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodoconsequat. ",
                "url":"#"
              }
            ,
              {
                "title":"Lenovo Tablet",
                "price":"75$",
                "description":"One of the most stylish tablets on the market. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.",
                "url":"" 
              }
            ,
              {
                "title":"Asus Tablet",
                "price":"100$",
                "description":"One of the most handy tablets on the market. Ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor",
                "url":"#"
              }
          ]
        }
      }
    ]
  }
}

Result (in the recipient's inbox):

 


Accessing an embedded object

Allows you to access the variables found in the substitutions object.

Substitution example: (parameter global_substitutions — email/sendtemplate/set ; substitutions — email/send):

...
"substitutions": 
{
    "person": 
    {
        "name":"John",
        "secondName":"Doe",
        "age":"26"
    }
}

 

Usage example: (parameters body.html, body.plaintext, body.amp, subject, headers, options.unsubscribe_url, from_name — email/sendtemplate/set):

 
"html":"<h2>Hello, $person.name $person.secondName !</h2>"

 


Array iteration (in embedded object / array)

Returns and iterates the elements of the array of substitutions.

 

Substitution example: (parameter global_substitutions — email/sendtemplate/set ; substitutions — email/send):

 

...
 "substitutions": 
        {
          "petList": 
            [
                {
                  "name":"John",
                  "price":"30"
                },
                {
                  "name":"Harold",
                  "price":"15"
                }
            ]
        }

Usage example: (parameters body.html, body.plaintext, body.amp, subject, headers, options.unsubscribe_url, from_name — email/sendtemplate/set):

 
"html":
 "#foreach( $pet in $petList )
    $pet.name for only $pet.price
 #end"

 

Substitution example: (parameter global_substitutions — email/sendtemplate/set ; substitutions — email/send):

 
...
 "substitutions":
        {
          "DogsAndCats":
            [
              {
               "pet":
                 [
                  {
                   "concreteAnimal":"Brown Cat"
                  }
                 ]
              }
            ]
        }

Usage example: (parameters body.html, body.plaintext, body.amp, subject, headers, options.unsubscribe_url, from_name — email/sendtemplate/set):

 
 
"html":
"#foreach( $pet in $DogsAndCats)
  #foreach( $concreteAnimal in $pet.pet)
    Buy this $concreteAnimal.concreteAnimal
  #end
#end"

 


Call the Nth array element

Сalls the array element with a specified index.

 

Substitution example: (parameter global_substitutions — email/sendtemplate/set ; substitutions — email/send):

 
...
 "substitutions": 
        {
          "petList": 
            [
                {
                  "name":"John",
                  "price":"30"
                }
            ]
        }

Usage example: (parameters body.html, body.plaintext, body.amp, subject, headers, options.unsubscribe_url, from_name — email/sendtemplate/set):

 
"html":
"$petList.get(0).get("name")"

 


Access the index of the current array element

Returns the current array index.

 

Substitution example: (parameter global_substitutions — email/sendtemplate/set ; substitutions — email/send):

 
...
 "substitutions": 
        {
          "catsArray": 
            [
              "cat":"black" 
            ]
        }

Usage example: (parameters body.html, body.plaintext, body.amp, subject, headers, options.unsubscribe_url, from_name — email/sendtemplate/set):

 
"html":
"#foreach( $cat in $catsArray )
  Index of $cat is  $catsArray.indexOf($cat)
#end"

 


Convert to lowercase

Converts the string to lowercase.

 

Substitution example: (parameter global_substitutions — email/sendtemplate/set ; substitutions — email/send):

 
...
 "substitutions": 
        {
          "UpperCASE":"TEST" 
        }

Usage example: (parameters body.html, body.plaintext, body.amp, subject, headers, options.unsubscribe_url, from_name — email/sendtemplate/set):

 
"html":
"$UpperCASE.toString().toLowerCase()"

 


URL and HTML escaping

Replaces URL and HTML special characters with the correct entities.

 

Substitution example: (parameter global_substitutions — email/sendtemplate/set ; substitutions — email/send):

 
...
 "substitutions": 
        {
          "url": "hello here & there",
          "html_code":"\’bread\" & \"butter\’"
        }

Usage example: (parameters body.html, body.plaintext, body.amp, subject, headers, options.unsubscribe_url, from_name — email/sendtemplate/set):

 
"html":
"$esc.html($html_code)
$esc.url($url)"

 


Date and time formatting

Returns the "date" data type in a convenient format for further usage.

Note: the variables for substitutions of the "date" data type should begin with "date_" for correct processing, e.g. "date_Birthdate"

 

Available date formats:

  • dd/mm/yyyy

  • dd-mm-yyyy hh:mm:ss

  • yyyy/mm/dd HH:mm:ss

  • yyyy mm dd HH:mm:ss

  • ISO 8601 2004-02-12T15:19:21+00:00

  • RFC 2822 Thu, 21 Dec 2000 16:01:07 +0200

 

Substitution example: (parameter global_substitutions — email/sendtemplate/set ; substitutions — email/send):

 
...
 "substitutions": 
        {
          "date_Birthdate":"01/01/1970" 
        }

Usage example: (parameters body.html, body.plaintext, body.amp, subject, headers, options.unsubscribe_url, from_name — email/sendtemplate/set):

 
"html":
"$dateFormat.format('yyyy-M-d', $date_Birthdate)"

$dateFormat.format changes the format of the passed date. The following formats are available:

 

 $date                                    -> Oct 19, 2003 9:54:50 PM
 $date.long                             -> October 19, 2003 9:54:50 PM PDT
 $date.medium_time                -> 9:54:50 PM
 $date.full_date                       -> Sunday, October 19, 2003
 $date.get('default','short')       -> Oct 19, 2003 9:54 PM
 $date.get('yyyy-M-d H:m:s')   -> 2003-10-19 21:54:50

 
 

If/else conditions

Allows you to insert if / else conditional statements into the email template.

 

Substitution example: (parameter global_substitutions — email/sendtemplate/set ; substitutions — email/send):

 
...
 "substitutions": 
        {
          "shoeSize":"5" 
        }

Usage example: (parameters body.html, body.plaintext, body.amp, subject, headers, options.unsubscribe_url, from_name — email/sendtemplate/set):

 
"html":
"These shoes are  
  #if( $shoeSize > 5 )
      too big
  #elseif( $shoeSize < 5 )
      too small
   #else
      just right
   #end
   for my brother."

 

Apache Velocity template engine can handle objects and arrays substitutions using loops and if/else conditions. This will significantly reduce the time spent on the same letter templates development or development of the template parts. Using Velocity once is enough to create a pattern, which will be filled automatically by structured substitutions processed in the request. Depending on the conditions specified in the template, Velocity will handle substitutions, replacing the variables with the values ​​or transforming their values ​​by a given algorithm. Using complex substitutions (objects, arrays) will also reduce the size of requests, thereby increasing the processing speed, and speed up sending emails as a result.

For more information about Velocity functionality supported by UniOne: Velocity use cases

Using Velocity in UniOne allows you to use the substitutions with objects and arrays to create emails with dynamic content. This significantly reduces the size of the traffic and automates the process of creating templates with identical structures that differ only by the content.

 

 

The substitutions can be used in the following parameters (methods email/send and template/set):

  • body.html
  • body.plaintext
  • body.amp
  • subject
  • headers
  • options.unsubscribe_url
  • from_name

Velocity use cases

This template engine substitutes data fields surrounded by double curly braces. For example, if you have recipient's name in Name field you can use this expression: {​​{Name}}.

There are a couple of extra possibilities also (they do not work inside links thou):

HTML example Description
{ ​{ Name|Dear Subscriber } } 

 

This tag will be replaced by the value of the field “Name”, and if “Name” is empty, it will be replaced by «Dear Subscriber» as if it was a «default value» of the field. Instead of the text, you can specify the name of another field, for example:
{ { Name| { { Email } } } }
{ { HasOrders?You have 10% discount } }

If the field “Has Orders” is not empty and not equals zero, it will be replaced by the text «You have 10% discount», otherwise the result will be an empty string.
Instead of the text you can specify the name of another field, for example:

{ { HasOrders? { { Discount } } } }

Look at more complicated example, which adds comma before the name, but only if name is not empty: 

Congratulations { {Name?, } } { { Name } }!

Each email sent with email/send method or each template referenced by group of template methods is using one of the two supported template engines:

Templates allow send emails faster and make them more personalized, so take your chance to learn their abilities.

If you see an exclamation mark in the upper left corner of your account screen along with a notice “Sending disabled”, or you receive an API error 215 error “The user is not allowed to send email”, this means that mailing has been disabled for your account.

This may happen due to the following reasons:

  • You have not paid one or more bills, and a number of charging attempts we’ve made were unsuccessful. Please be sure to check all due invoices on your Billing/Invoices page. If any questions arise, do not hesitate to contact our support. As soon as we receive your payment, you may resume mailing.
  • Our automatic spam prevention system sees some of your activity as highly suspicious. If you believe the system is wrong, please contact our support team. The accident will be promptly investigated, and we’ll fine tune the system to prevent similar occasions in the future.
  • Support team members could also have manually disabled the mailing function for your account. Contact us to find out why.

This measure being an extremity, we still have to resort to it on certain occasions, since UniOne’s high deliverability attracts spammers quite often.

You can send emails with UniOne using one of the following methods:

Web API - fast, efficient, and with many features allowing you to integrate it with your site through programming.

SMTP API - less throughput, but all you need to do is enter the host, login, and password - and you're ready to go.

Integrations - to use UniOne with third-party services.

We offer following integrations and libraries:

If you're interested in UniOne plugin for a particular service or need a library for another programming language, please contact our support.

May 22, 2024 (v.1.61)

Sep 27, 2023 (v.1.52)

  • added the option to process certain headers "To:", "CC:", and "BCC:" for SMTP - with strict compliance to the SMTP specification, where "To:", "CC:", and "BCC:" MIME headers will be included as-is. To enable this option, set the "strict" parameter value to "true" in the X-UNIONE header. Alternatively, you may contact support to enable this option for all letters by default, without having to add an extra parameter. More details in SMTP API.
  • added a new system unsubscribe language, "kz". The full list of supported languages: be, de, en, es, fr, it, pl, pt, ua, ru, kz.
  • new webhook event "subscribed" added. You may add to the list of events you already track.

May 11, 2023 (v.1.46)

  • new email validation method added email-validation/single.
  • passing List-Unsubscribe-Post header allowed now if you have a right to turn off standard unsubscribe footer.

Mar 1, 2023 (v.1.44)

  • new backend_id parameter in project/create, project/update, project/list methods.
  • message.custom_backend_id and message.smtp_pool_id parameters in the email/send method call may now be utilised by all users without having to contact technical support.

Feb 14, 2023 (v.1.44)

  • new message.bypass_global, message.bypass_unavailable, message.bypass_unsubscribed and message.bypass_complained parameters for email/send method call.

Dec 23, 2022 (v.1.41)

  • email/send method has been updated to support message.tags parameter.
  • two new methods for tag management have been added, tag/list and tag/delete.
  • statistical charts were modified to support filtering by tags and campaign id.

Oct 18, 2022 (v.1.38)

  • new event-dump/* methods were added which implement export of event data in CSV format.
  • If you are allowed to disable the Unsubscribe link, you may fully disable the template engine by specifying "template_engine":"none" in email/send or SMTP call.
  • the "campaign_id" metadata field has got a special function: it can now be used with event-dump/create method call to filter events related to a given campaign . A similar option will later be added for filtering statistical data for diagrams in your account. If you need to use a different variable name for this purpose, please contact our support.

Jun 24, 2022 (v.1.34)

  • new methods added: suppression/set and suppression/list
  • it's allowed to pass References and In-Reply-To headers in addition to the List-Unsubscribe header for users with the right to remove unsubscribe footer

Mar 18, 2022 (v.1.31)

Feb 23, 2022 (v.1.30)

  • new message.options.send_at parameter for email/send method call.
  • added the ability to change the language of the unsubscribe footer using message.global_language parameter or the X-UNIONE-Global-Language in message.header.
  • added the ability to select a template engine through the X-UNIONE-Template-Engine in message.header.

Dec 28, 2021 (v.1.28)

Jul 5, 2021 (v.1.19)

  • added several new languages support for unsubscribe page. The full list of supported languages: be, de, en, es, fr, it, pl, pt, ru, ua.

May 31, 2021 (v.1.17)

  • new email/send parameter message.options.custom_backend_id.

Mar 17, 2021 (v.1.16)

  • API POST request size limit was incremented to 10MB, HTTP code 413 / API code 199 is returned in case of a larger request.

Feb 24, 2021 (v.1.15)

  • 2 days retry guarantee for messages with soft_bounced status.
  • new email/send parameter message.options.smtp_pool_id.
  • added "es" and "ua" languages for unsubscribe page.
  • some returned HTTP codes changed to correspond with API error codes. You can find full list here.

Jan 4, 2021 (v.1.14)

  • new authentication method added: passing API key in HTTP header X-API-KEY
  • passing List-Unsubscribe, List-Subscribe, List-Help, List-Archive, List-Owner headers allowed now if you have a right to turn off standard unsubscribe footer
  • Substitutions (merge tags) are now supported in header values.

Dec 7, 2020 (v.1.13)

  • new webhook/list method added
  • new "status" field for webhooks with possibility to disable and activate webhooks without deleting
  • auto-stop with email notification of webhooks constantly failing during 24 hours (minimum 10 calls)

Nov 20, 2020 (v.1.12)

Oct 16, 2020 (v1.11)

Sep 24, 2020 (v.1.10)

  • new "skip_unsubscribe" and "force_send" parameters added to email/send method
  • email/send parameter "metadata" renamed to "global_metadata", but old name is still accepted for backward compatibility
  • email/subscribe parameters renamed to match email/send parameters, but old names are still accepted for backward compatibility

June 03, 2020 (v.1.7)

March 03, 2020 (v.1.5)

  • username parameter in all methods is now ignored, user is authorized only by api key
  • user_id field has been added to webhooks
  • obsoleted methods removed: checked_email, set-domain, validate, getCheckedEmail, getSenderDomainList, setSenderDomain, validateSender

Web API UniOne allows you not only to send emails lightning fast, but also to deal with unsubscribes, domains, separate projects or to get statistics with webhooks. You can browse all the methods in our Web API Reference.

All UniOne API methods require an HTTPS connection. UniOne accepts HTTP POST requests in JSON format up to 10 megabytes long and returns an HTTP response also in JSON. In case of error the JSON body with an error description and an API error code is returned, but you will also receive a corresponding HTTP return code. You can read more about error handling here.


You should send an API request to the server your account is registered at:

 

SMTP allows sending up to 5000 emails per hour using single connection, and with 10 maximum permitted connections it could be up to 50 000 emails per hour. Web API allows sending up to several millions emails per hour, so consider using Web API if speed is your priority. But the good news is that SMTP integration is very simple, you just need to set some connection parameters. And don't forget to read our emails about API updates or take a look on changelog periodically.

SMTP Connection parameters

  • host: either smtp.us1.unione.io or smtp.eu1.unione.io (for accounts registered at us1.unione.io and eu1.unione.io, respectively).

  • port25, 465 or 587. Only encrypted TLS connections are supported, with recommended version 1.2 or higher. We provide no support neither for unencrypted port 25 SMTP connections nor for encrypted SSL connections due to security reasons. TLS 1.0 and TLS 1.1 support was terminated in the middle of 2021.

  • usernameuser_id (you can see it in the upper left corner of the screen under your email after login) or project_id (you can get it by project/create or project/list method, and also on Projects page).

  • passwordAPI key of your account or project_api_key (you can get it by project/create or project/list method, and also on Projects page)

  • encoding: connection encoding should be set to UTF-8

Extended features

You can use extended features of UniOne while sending thru SMTP, such as substitutions(merge tags), templates, link and read tracking.To access these features you should pass an extra header X-UNIONE with parameters in JSON format. Many parameters from email/send are supported together with extra parameter "global_language". E.g.:

{
  "global_language": "en",
  "template_engine": "velocity",
  "template_id": "5c046a8b-6f6b-4f0b-a5b6-1d0ff8953ac7",
  "global_substitutions": {
    "DiscountCode":"XMAS",
    "Name": "John"
  },
  "global_metadata": {
    "meta-campaign": "transactional"
  },
  "track_links":1,
  "track_read":1,
  "skip_unsubscribe":0
}

All supported X-UNIONE JSON parameters

Name Type Description
template_engine Optional string Sets the template engine for handling the substitutions. Accepts values: "simple" и "velocity". If the parameter is not passed, the system will use the default value - "simple"
template_id Optional string Optional identifier of the template that had been created by template/set method or in UniOne web interface.
global_language Optional string Language used for unsubscribe footer and unsubscribe page interface. "en" by default. Supported languages: be, de, en, es, fr, it, pl, pt, ru, kz, ua. You can ask our support if you need other languanges.
global_substitutions Optional object Object for passing the substitutions (e.g., first name of recipient).
global_metadata Optional object Object for passing the metadata, such as "key" : "value". Max key quantity: 10. Max key length: 64 symbols. Max value length: 1024 symbols. The metadata is returned by webhook. To logically group a number of emails into a single campaign, you may specify the campaign_id parameter which can be either an unsigned decimal integer or a UUID with a maximum length of 128 bits.
track_links Optional boolean
  • 0 - click tracking is off
  • 1 - click tracking is on (default)
track_read Optional boolean
  • 0 - email read tracking is off
  • 1 - email read tracking is on (default)
skip_unsubscribe Optional boolean
  • 0 - append a footer with unsubscription link to HTML body (default)
  • 1 - don't append a footer with unsubscription link to HTML body (but List-Unsubscribe header is still set if options.unsubscribe_url is not empty)

In order to use skip_unsubscribe=1 value you should ask support to enable it first.

strict Optional boolean

This parameter sets the way "To:", "CC:", and "BCC:" headers are processed (see also Implementation details):

  • false - each addressee listed in "To:", "CC:", and "BCC:" will receive their own copy (default value)
  • true - headers are processed with strict adherence to SMTP specs
tags Optional array An array of strings. The maximum string length is 50 characters. You can include up to 4 strings which must be unique. No more than 10 000 tags are allowed per project; if you try to add more, email/send will return an error. You may use tags to categorize emails by your own criteria, and they will be passed along by event-dump methods.

 

Implementation details

  • Maximum accepted email size is 10 megabytes.
  • Please don't forget that all headers, including X-UNIONE header, should be encoded according to MIME standard, if contain non-ASCII characters. The majority of programming languages have special functions for such an encoding. For example, in PHP it's a mb_encode_mimeheader function.
  • There's a limit of 300 bytes for header line length in UniOne. You should divide a header into several lines if it's longer than 300 bytes. Usually the same function that does MIME encoding also takes care of line splitting. For example, in PHP it's the same mb_encode_mimeheader.
  • Please note that unsubscribe link is automatically added to the footer of your email, unless you pass skip_unsubscribe=1 parameter in X-UNIONE header or ask support to disable unsubscribe link for all of your SMTP and API sent emails. Information about unsubscriptions can be obtained through webhooks or by calling suppression/get и suppression/list methods (where "cause"="unsubscribed").
  • Please note that by default UniOne deviates from the SMTP specification in the way it handles the "CC:" and "BCC:" fields. Each address listed in these fields will receive its own copy of the letter, in which the MIME To: header will contain that target address only, and original "To:" and "CC:" headers will be removed. Each copy will be charged for according to your tariff. Also, values for global_substitutions will apply to all copies; thus, for personalized emails it is advised to use single messages. If you need the SMTP specification to be followed strictly, with "To:" and "CC:" headers being left intact (which may be required to implement carbon copy and blind carbon copy functionality), you may set the strict parameter value to true in the X-UNIONE header (or, alternatively, contact tech support to have strict=true set by default for all of your letters, without having to specify the parameter in X-UNIONE. To prevent malpractices, we also perform additional validation on RCPT TO: it must contain only addresses that are present in "To:" and "CC:" MIME headers, or addresses on your own validated domains. The number of addresses in CC and BCC must not exceed 10 for each header, and BCC may contain only addresses on your verified domain.
  • The <body> tag is required to display the HTML content in case you are using the <html> tag. We won't accept an email without the <body> tag when the <html> tag is present.

Supported headers

We accept these headers:

  • standard "From", "To", "CC", "BCC", "Reply-To", "Subject" header (but they may be changed due to substitutions and other implementation details described above)
  • "List-Unsubscribe", "List-Subscribe", "List-Help", "List-Owner" and "List-Archive" headers are accepted in two cases:
    • either you have requested earlier and tech support has approved full removal of unsubscribe links for user_id/project_id used as SMTP login
    • or you have requested earlier and tech support has approved dynamic removal of unsubscribe links for given user_id/project_id AND you have passed skip_unsubscribe=1 parameter in X-UNIONE header
  • headers starting with "X-" are left "as is", with a limit of 50 headers.

All other headers are stripped out.

Response

After the sending SMTP API returns Id which can be used as a value of job_id in webhooks.

Test your SMTP connection

If you need to check whether your SMTP connection works correctly or find possible issues, try our free SMTP Debug Tool to run test sessions.