[Users] [Bug 4803] New: MS-Outlook SMTP server rewrites Message-ID header

[noreply at thewildbeast.co.uk]

https://www.thewildbeast.co.uk/claws-mail/bugzilla/show_bug.cgi?id=4803

            Bug ID: 4803
           Summary: MS-Outlook SMTP server rewrites Message-ID header
           Product: Claws Mail
           Version: GIT
          Hardware: All
                OS: All
            Status: NEW
          Severity: normal
          Priority: P3
         Component: SMTP
          Assignee: users at lists.claws-mail.org
          Reporter: ian_brce at outlook.com

It appears that when a message is transmitted through the Microsoft Outlook
SMTP server <smtp-mail.outlook.com> (or perhaps any Microsoft SMTP server), it
rewrites the existing Message-ID header with a new ID, but preserves the
original Message-ID in the proprietary header
"X-Microsoft-Original-Message-ID".

This bad design decision will have various bad effects, most obviously for
message threading, but perhaps other places as well.

It seems that for the purpose of message threading, both the Message-ID and
X-Microsoft-Original-Message-ID headers maybe should be considered.

Also, when replying to a message which contains both of these headers, they
should probably both be copied into the References header, to help the
recipient recognize the reply. The In-Reply-To header should probably use the
Microsoft-regenerated Message-ID.

Of course, this is a Microsoft-created problem, but it seems like a few small
program adjustments might help to work around it.

*****

other complaints about this problem:

https://answers.microsoft.com/en-us/outlook_com/forum/all/outlook-changes-the-custom-message-id-we-set-in/fe4f64dc-f97b-419d-a1ab-365a045426d0

https://learn.microsoft.com/en-us/answers/questions/1337178/custom-message-id-modified-by-the-outlook-smtp-ser

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