[Mimedefang] allow local aliases w/ md_check_against_smtp_server

[Ron Peterson]

I'd use md_check_against_smtp_server in filter_recipient.  I'd like to
add some local aliases, and not have md_check_against_smtp_server stomp
them.

I can easily put a wrapper around the call to to
md_check_against_smtp_server which would build a hash table for my
aliases file and check whether the recipient exists there, and if so,
skip the remote username check, but I'm concerned about the overhead of
doing this.  Can I do something more efficient?

-- 
Ron Peterson
Network & Systems Manager
Mount Holyoke College