Hello,
I can't guarantee because we use front end spam/virus scanners gateways instead of SM built-in (to lower the SM server load and add flexibility), but I think you can do this with the local or remote clamav.
There is a clamav setting: ArchiveBlockEncrypted
In recent clamav versions, it seems to be replaced by:
AlertEncryptedArchive BOOLAlert on encrypted archives (encrypted .zip, .7zip, .rar).
Default: noAlertEncryptedDoc BOOLAlert on encrypted documents (encrypted .pdf).
Default: no
This would need to be added in:
C:\Program Files (x86)\SmarterTools\SmarterMail\Service\Clam\etc\clamd.conf
That could maybe do the trick.
Sébastien Riccio
System & Network Admin
https://swisscenter.com