[Question] Remove These Headers and Outlook conversation view

Eoin Kim Eoin.Kim at rcst.com.au
Thu Feb 15 08:31:58 UTC 2018

Hi Mark,

Thanks for your reply. 

So, if MailWatch is configured to release quarantined emails as original and MailScanner is configured to remove Message-ID: header, no Message-ID: is generated during the release? Like the RFC 5322 says, if all messages should have Message-ID: header, shouldn't MTA generate a new Message-ID: by itself when releasing messages? Also, I am not sure whether Message-ID: header should be always unique or not. If it should be unique, then how Exchange server can group related messages in a conversation view in user's Outlook?

Ah... This looks way more complicated than I expected. Thanks again.


From: MailScanner <mailscanner-bounces+eoin.kim=rcst.com.au at lists.mailscanner.info> on behalf of Mark Sapiro <mark at msapiro.net>
Sent: Thursday, 15 February 2018 5:59 PM
To: mailscanner at lists.mailscanner.info
Subject: Re: [Question] Remove These Headers and Outlook conversation view

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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