Between Mailscanner and Amavisd-new, it seems we need one or the other of these programs to recursively dig into and possibly uncompress a message with attachments to be able to virus scan it completely. Does Mailscanner do as effective a job as Amavisd in this regard?
When I installed Amavisd a couple years ago now, I seem to remember a load of dependencies on things like rar, tar, unzip...etc. I didn't see a lot of these when I compiled Mailscanner. (Unzip, yes, but not some of the other ones). Michael Grant