Tag/ID incoming emails not encrypted with TLS in Microsoft 365

[gsk]

Hi All,

 

We've got DMARC and MTA-STS set up with TLS reporting, but I wanted a way where I could put a tag in the subject line of an incoming email that wasn't sent using TLS. This is so that, rather than blocking an incoming message outright, it's at least tagged for caution so that the user is aware.

 

Does anyone have any thoughts on how to achieve this in Microsoft 365?

 

Thanks,