Postfix + Mailman

I have been attempting to set up an email listserver for a couple days now, and I finally fixed the problem. It was:

|/usr/local/mailman/mail/mailman post list"@domain.tld>
(expanded from ): unknown user:
"|/usr/local/mailman/mail/mailman post list"

The solution, when it came, was simple. What had happened was the aliases were being mapped to the virtual list, and so it wouldn't handle the external command execution properly. The solution? Just make sure that virtual_alias_maps doesn't have $alias_maps as one of its values. :-D