There are some domains on my server that want virus and spam scanning but do not want any attachments blocked. How can I set this up?

In the /usr/mailscanner/etc/rules/ directory, edit filename.rules.rules and filetype.rules.rules (and the archives.filename.rules.rules and arvhies.filetype.rules.rules if you also want the same rules for scanning within zip archives). Add a line like this for each domain for which you don't want attachments to be scanned:

For filename.rules.rules add:

FromOrTo: domain.com /usr/mailscanner/etc/filename.no.rules.conf

For filetype.rules.rules add:

FromOrTo: domain.com /usr/mailscanner/etc/filetype.no.rules.conf

The files /usr/mailscanner/etc/filename.no.rules.conf and /usr/mailscanner/etc/filetype.no.rules.conf should simply contain the following line:

allow   .       -       -

Make sure that you put tabs and not spaces between the parts of the above line.