Transport Rule BCCs email to external address but converts email from HTML to Plain Text

jb-dd 1 Reputation point
2022-10-07T17:52:49.54+00:00

Hello, we are using Office 365 Exchange Online and I have a transport rule setup to BCC any email received in a specific mailbox to an MDaemon server we host onpremises. When this transport rule kicks off, it appears to be converting the emails from HTML to Plain text, which is breaking one of our 3rd party importing tools. Is there any way to force emails to HTML in the transport rule, or by other means?

I've looked over the Mdaemon settings and I believe I have all the settings correct there, which leads me ot believe that the transport rule may be at fault.

Microsoft Exchange Online Management
Microsoft Exchange Online Management
Microsoft Exchange Online: A Microsoft email and calendaring hosted service.Management: The act or process of organizing, handling, directing or controlling something.
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  1. Andy David - MVP 142.6K Reputation points MVP
    2022-10-07T18:52:03.097+00:00

    Is there a remote domain defined for that MDaemon server?
    You could set the remote domain content type to MimeHtml and see if that helps.
    otherwise, I tend to blame the receiving server or client for these issues, not a transport rule.
    If you were to BCC another remote contact in that rule, I would wonder what format it is for that receiving client.

    https://learn.microsoft.com/en-us/powershell/module/exchange/set-remotedomain?view=exchange-ps

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  2. jb-dd 1 Reputation point
    2022-10-07T19:17:18.917+00:00

    Thanks for the reply! I don't have remote domain setup so I can talk to my systems engineer about that.

    I was incorrect in my first statement. that it was converting from HTML to plain. It's actually a 'multipart/alternative' content type message. I pulled a copy of an email from the MDaemon server and saw that it's a MultiPart content type, starting with the Plain version and then the HTML version.

    the original email that it BCCs to MDaemon is Content-Type: application/ms-tnef; name="winmail.dat".

    I might try setting up these email addresses as a 'contact' and applying the TNEF conversion policy.

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  3. Andy David - MVP 142.6K Reputation points MVP
    2022-10-07T19:23:40.393+00:00

    Yep, setting the contact conversion type is something else i was thinking. Thats always been a good work-around!

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