I find the documentation available for amavis to be incomplete especially in regards to block and scan rules.

I want to make sure that zip files are not blocked by extension but are still scanned for viruses.

The categories in the default amavisd.conf are:
allow
blocked anywhere
allow, stop looking if zipped
block the following except within unix archives
block the following except within archives
block certain double extensions
banned extensions

I need a category for:
Allow extension, then scan for viruses

blocked anywhere syntax:
qr'^\.(blah|blah2)$'

allow, stop looking if zipped:
[qr'^\.(blah|blah2)$=> 0]

banned extensions
qr'^.\.(blah|blah2)$'i,

In general this syntax is arcane enough but for some reason over at the amavis project they think we'll just be able to guess at these settings and the 10k+ threads like this one I found asking for every specific case other than what appears in the official docs seems to confirm. tia, especially if anyone can point out a manual where these things are actually explained.