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New: endpoints for creating and updating themes and components.
New: Guardian endpoint for validating email message content via the API.
New: a transactionalName field in the transactional.email.sent webhook event.
New: endpoints for viewing workflows and workflow nodes. These endpoints are currently in open alpha.
New: endpoints for campaign groups, transactional groups, audience segments, and email message previews.Updated:
  • Campaign endpoints now support audience targeting (mailing list, segment, or filter), groups, and scheduling.
  • Email message endpoints now support CC/BCC, language, email format, and property fallbacks.
  • Transactional email endpoints now support groups.
New: endpoints for creating and editing transactional emails. These endpoints are currently in an open alpha.
New: Upload endpoints for uploading images to use in emails.
New: endpoints for creating and editing campaigns. These endpoints are currently in an open alpha.
New: API endpoints to check and remove suppression for contacts.
New: a campaignName field in the campaign.email.sent webhook event.
New: an email.resubscribed webhook event for when contacts resubscribe to your marketing email from an email’s “Unsubscribe” link.
New: an optInStatus field from double opt-in in the Find contact endpoint and in contact.created webhook events.
New: webhooks are now available to all users.
Improvement: all endpoints now return a success and message field in the error response bodies.error and path top-level keys are now deprecated but will continue to be supported for some time for backward compatibility.
The docs have been updated to reflect that the email parameter is optional in the Update contact endpoint if a userId is provided.
Improvement: data variables are now optional in the Send transactional email endpoint. Read more
New: an Idempotency-Key header when sending events.
New: an Idempotency-Key header when sending transactional emails.
New: an endpoint for listing transactional emails and their data variables.
New: webhooks are in Beta.
New: new endpoints for creating contact properties and listing contact properties.Deprecation: the List custom fields endpoint is now deprecated in favor of the new List contact properties endpoint.
New: we added description to mailing list objects in the List mailing lists endpoint.
Improvement: the maximum payload size for the transactional endpoint has been increased from 1MB to 4MB, allowing for more or larger attachments.
New: our new Nuxt module is now out!
New: our new Ruby SDK is available!
New: we added an isPublic attribute to mailing list objects in the List mailing lists endpoint.
New: there’s a new addToAudience parameter in the Send transactional email endpoint that can add contacts to your audience.
New: support for our new mailing lists feature.You can now add contacts to and remove contacts from mailing lists in the Create contact, Update contact and Send event endpoints.There is also a new endpoint for retrieving your mailing lists.
New: you can now Find contacts by userId.
New: a new endpoint for testing your integration and/or API key: API key.
New: you can now include event properties in requests to the Send event endpoint.
Improvement: we removed behavior that returned a 400 Bad Request response if an unrecognized property was added to Contact endpoints.
Improvement: sending in a payload that contains an unrecognized property will now return a 400 Bad Request response.
Clarification in the API docs that userId can be used in a Send event request.
New: we added a new endpoint for querying custom contact properties.
New: we now accept dates as a custom contact property type. View the available formats.
Last modified on July 9, 2026