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I have a piece of software that is sending multiple e-mails.
The first one has the header

Message-ID: <153495492389.29001.486258560116169081@server.example.com>

The second and all following ones have the headers

In-Reply-To: <153495492389.29001.486258560116169081@server.example.com>
References: <153495492389.29001.486258560116169081@server.example.com>

But it seems that this is not enough for Outlook to display those messages as conversation, even if showing conversations is enabled.

Can someone enlighten me what is necessary so that the mails can properly shown as conversation in Outlook?

Vampire
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2 Answers2

7

Bugzilla to the rescue, they found out what to do a couple of years ago already at https://bugzilla.mozilla.org/show_bug.cgi?id=411601.

The key is the Thread-Index header. It is a Base64 encoded sequence of some bytes and has amongst other fields a UUID field which is significant for the grouping.

The exact format is defined at https://msdn.microsoft.com/en-us/library/ee202481%28v=exchg.80%29

Vampire
  • 303
0

For Internet mail accounts and newer versions of Exchange accounts, the Conversation group feature uses a Conversation ID filed to identify if a message belongs to a conversation. You can use the MFCMAPI tool to view the Conversation ID filed: enter image description here

Reference: Conversations View (Show Messages from Other Folders)

Yuki Sun
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