Sep 24, 2026 (v.1.91)
- New traffic_type field added to the delivery_info object of webhook “opened” and “clicked” events. It shows who most likely opened the email or clicked the link: human (a recognized browser or email client), machine (a bot, link scanner or security proxy), protected (a mailbox or OS privacy proxy such as Apple Mail Privacy Protection or Gmail Image Proxy, where a human action can’t be confirmed) or unknown (the user agent is missing or not recognized).
- Maximum tag length in the tags parameter of email/send increased from 50 to 100 characters.
Aug 13, 2026 (v.1.90)
- Device info added to the delivery_info object of webhook “opened” and “clicked” events: device_type, device_brand, os_name, browser_name and email_client_name. All values are detected from the recipient’s user agent.
Jun 04, 2026 (v.1.87)
- Recipient geolocation added to the delivery_info object of webhook “opened” and “clicked” events: country_code, country and city, detected from the recipient’s IP address.
- New sender_ip field added to the delivery_info object of webhook “delivered”, “soft_bounced” and “hard_bounced” events. It contains the IP address of the SMTP server that sent the email, if available.
Apr 11, 2026 (v.1.85)
- System-ping API Method added. This method checks API key validity and returns user ID.
Aug 04, 2025 (v.1.76)
- New email delivery status added — “accepted”.
Mar 27, 2025 (v.1.72)
Jan 09, 2025 (v.1.69)
- email/send method has been updated to support message.idempotence_key parameter.
Oct 11, 2024 (v.1.66)
- Domain/delete API Method added. This method allows the deletion of the domains directly via the API.
Sep 17, 2024 (v.1.64)
- Enhanced Email Counter Configuration. You can now configure and control the email counter in the project (email_counter, email_counter_limit, and email_counter_mode) using the project/update method.
- Additionally, it’s now possible to retrieve the current values of email_counter, email_counter_limit, and email_counter_mode via the project/list and system/info methods.
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 01, 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.1.43)
- 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)
Jun 05, 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 04, 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 07, 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 (v.1.11)
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
Jun 03, 2020 (v.1.7)
Mar 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
