We plan on implementing this functionality, although we do not have any timelines to share at this stage.Travis supported this idea ·Travis commented
Definitely need this feature....If TLS fails when sending/receiving with external users, then automatically apply OME (Office 365 Message Encryption). Currently the thing close to this is using Mail Flow Rules to 'Require TLS' and if it fails then the message fails outright.
The desired function would be to add to this rule so if 'Require TLS' fails, then 'Apply O365 Message Encryption and rights protection to the message...' then select RMS Template 'Encrypt'. Please add this feature MSFT.