Hello Josh, 

The reason you are seeing this is that the Alias address ( Mailing List address as well ) is not expanded untill the message hits the Delivery Thread after being accepted by the SMTP thread. 

I can submit a Feature Request to adjust how these are handled. 

Thank you

Feature request, please! Anything to lower the impact of spams is welcome!

BTW, maybe consider a meta feature request that I have asked for several times that would allow me to fix this problem myself: a new command line file like the one currently available in spool, except that it get run on new messages received over SMTP after the message terminating period but before the server sends the completion reply. If the new command line program deletes the message files then the server would return a reject message. Even better would be if the command line could tell the server the response line to return to the other side. This would open up so many great new ways to control spam with proper rejects going back to the sending party!

Thanks!

-josh