Custom Fields in the Core API
The Core API now exposes endpoints to list the custom fields that can be used on different resources:

• Use GET /accounts/custom_fields to list the custom fields available on an Account (docs).
• Use GET /contacts/custom_fields to list the custom fields available on a Contact (docs).

• Use GET /conversations/custom_fields to list the custom fields available on a Conversation (docs).
• Use GET /inboxes/custom_fields  to list the custom fields available on an Inbox (docs).
• Use GET /teammates/custom_fields  to list the custom fields available on a Teammate (docs).

In addition, the Custom Field data model now returns all the supported values for the Custom Field of type enum.

Accessing email messages in the .eml format

The Get message (GET /messages/:message_id) endpoint now supports customizing the response's Content Type.

By default, the endpoint returns the documented JSON data. However, you can now request the response to contain the message in the .eml format by setting the HTTP Header Accept to message/rfc822.

Note that this format is only supported for messages of type email. Requesting this format for any other message type will result in a JSON error response.