Virus Scanning moved imap files

[Shelley Waltz]

I have two imap servers, one which has smtp(postfix) and virus scanning
before delivery to imap.

I have another imap archive server which has no smtp, but users simply
move messages from their imap account(s) to the archive server.  It appears
that some messages have infections.

My question is, other than wholesale scanning the entire imap directory, moving
infected messages to a virus folder, and reconstructing the mailbox, is there a
more elegant way?  One which scans on arrival before depositing into inbox?

Any creative suggestions are appreciated.
SWaltz