Longboard

CJ - would you mind sharing some notes on the SMTP headers used to accomplish this?

Quoting from the article above, "If one of these lines uses a static message-ID or email address", where "these" refers to the In-Reply-To and References headers.

It also mentions using the References header. If the References header has a value such as support+id1234@domain.tld, does Zendesk honour that as a link to the original ticket of 1234 for comment? Or does it only use the original message-id and only in the In-Reply-To header?

Is there any way to have an email reply processed by Zendesk as a comment on an existing ticket, without the original message-id in the In-Reply-To header?

We tried adding the ticket email address to the "References" header, but that just resulted in the message being flagged with the error "Permission denied due to unauthenticated email update".