Problem
You get emails about some other emails did not get scanned by Amavis for unknown reason.
Parts of the emails look like this:
No viruses were found.
Content type: Unchecked
Internal reference code for the message is 64939-03/YKM8aTKSrtb7
This is an informative email when some parts of the email could not be scanned (i.e. encrypted or compressed content).
Solution
Disable these messages (these emails will still not being scanned for viruses!) as follows:
Edit the file /etc/amavis/conf.d/99-personal-setting and make sure entries as follows exist:
use strict;
$admin_maps_by_ccat{+CC_UNCHECKED} = undef;
Restart Amavis:
systemctl restart amavis.service