Email messages that your application distributes are missing headers.
This issue might be caused by the following implementation flaws:
- Overridden Service Email rule definition, to enable selecting an unsupported message header type.
- Exceeded the limit for the maximum number of custom headers in a message.
- Formatted the header name improperly.
- Customize headers by using an activity to send emails. Ensure that your
configuration meets the following requirements:
- The message does not include more than five custom headers.
- The header name has the following format:
For more information, see the REST Microsoft Graph API documentation. Note: The x character is case-insensitive.
- If you use a Service Email rule, for each response header, ensure that
the Field Name parameter value is either
Subject or From.
The following figure shows a sample response header in a Service Email rule: Note: Do not customize the Service Email rule definition to include additional header types from the Field Name list.