We currently use MimeSweeper for SMTP to scan all of our external email. We are looking to swap over to another product that has most of the same features except email aliases.
The Aliases are used to redirect many external email addresses to a single address. This is then forwarded to a single mail in database.
You can create “dummy” Group Documents that will point the additional aliases to an existing Mail-in database. When I say “dummy,” you can start the Group name with a common word, like “Alias-,” and then fill in the rest to direct an additional alias to the existing mail-in database name.
I am sure that others will chime in with a better solution.