How can I maintain conversations in MS Outlook using email headers?

Question

I have the following problem. My java code is sending emails using smtp mail server. This emails have to be grouped in some sort of threads (like conversations in Exchange). And this conversations have to be viewed properly (as conversations :-)) in MS Outlook. Is there some email headers that could be utilized. I've bumped into "In-reply-To" header, but it doesn't seem to do the trick in Outlook. Any suggestions?

Thanks you in advance.

The proper header to use is References: but I don't know whether Outlook honors it; Microsoft have a devastating track record when it comes to these things. See also cr.yp.to/immhf/thread.html — tripleee
The Discourse guys went through this, it sounds like using both In-Reply-To: and References: does the trick, though it's not entirely clear and I haven't verified this. meta.discourse.org/t/emails-are-not-threaded-in-outlook-2013/… — gregmac

Dmitry Streblechenko Dmitry Streblechenko · Accepted Answer · 2014-01-09T16:36:12

Use Thread-Index MIME header. See Tracking Conversations on MSDN for details on how PR_CONVERSATION_INDEX property is constructed.

How can I maintain conversations in MS Outlook using email headers?

1 Answers