Python O365 library detect encrypted Emails

I am trying to detect if incoming emails to my O365 account is encrypted or not.

The email sender can use any email provider like Gmail, Outlook, Yahoo etc.

At the moment i am able to detect encrypted message from outlook with below condition: len(list(filter(lambda x: x.name.lower().endswith(".rpmsg"), message.attachments))) > 0 where message is O365 Message object.

Is there a more general method i can use?

PS - Python O365 or any built in libraries are preferrable

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