MISSING_MIMEOLE Message has X-MSMail-Priority, but no X-MimeOLE

[mantoze]

I got this message in mailtrap.io "Spam check":
MISSING_MIMEOLE Message has X-MSMail-Priority, but no X-MimeOLE

Is all good with this header?

SpamAssassin Rule: MISSING_MIMEOLE

Standard description: Message has X-MSMail-Priority, but no X-MimeOLE

Explanation

The message is pretending to be generated by a Microsoft email program which uses the extension header X-MSMail-Priority, but is missing the extension header X-MimeOLE which is characteristic of Microsoft email.

This suggests that the sender is using badly-written mailout software, rather than a genuine Microsoft email program.

[xhit]

If you use Outlook SMTP you can get that warning if you set the priority in email to send.

To avoid the warning, skip the priority. If you really need it, maybe adding header using AddHeader method can solve this problem, but I don't test it, I don't have a Microsoft Outlook email, so test and let me know

email.AddHeader("X-MimeOLE", "Produced By My App v0.0.1")

Note, if works, only use it when you set low or high priority (If you always get the warning, use always if works).

[mantoze]

Yes, this header solved the problem.
Thank you.

[krystofklima]

I am trying to find same solving of problem. But where I can add

email.AddHeader("X-MimeOLE", "Produced By My App v0.0.1")

I try to google how to add to Outlook this, but with no success.
is it writeable to registry or some next place ??

[xhit]

Hi @krystofklima.

You need to add this in this package if you use it as email sender.

In README you can find the doc how to use it.