Question

I am trying to embed an ID into an email so that when a recipient replies to an email that my system sends out, my system can pick it up and match the two together.

I have tried appending a custom header, however this is stripped out when the user replies.

I have tried embedding an HTML comment within the email, but outlook does not seem to keep comments when a reply email is created.

Worst case scenario, I can manually try and match the sent and received emails by time span or have a visible tag within the message body.

Does anyone know of a more elegant solution?

Thanks in advance

Answer 1

Email messages already contain such an identifiers, called Message-ID. And there’s even a way to send which message you’re replying to by sending that ID in a header called In-Reply-To. That’s done by pretty much all email clients, that’s how they usually do their threading.

It’s defined in RFC 822 (yep that’s pretty old) and probably re-defined and refined in more modern versions of that.