[Question] Remove These Headers and Outlook conversation view

Mark Sapiro mark at msapiro.net
Thu Feb 15 07:59:46 UTC 2018

On 02/14/2018 05:44 PM, Eoin Kim wrote:
> My question is: does removing Message-ID header will make receiver’s
> Outlook conversation view impossible? My senior person says Message-ID
> might be used for conversation view. I am not really familiar with
> Windows servers so I am not sure what the background mechanism is in
> Exchange server.

The short answer is removing or altering Message-ID: headers will almost
certainly cause more problems than it solves.

I can't speak to Outlook in particular, but almost all mail agents rely
on Message-ID:, References: and In-Reply-To: for threading or
"conversation" view.

Also, RFC 5322 and predecessors say all messages SHOULD have a
Message-ID:, and while I can't speak specifically about Exchange, it is
possible that Exchange would not deliver a message without one.

Mark Sapiro <mark at msapiro.net>        The highway is for gamblers,
San Francisco Bay Area, California    better use your sense - B. Dylan

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