I tried adding a rule to /etc/aliases which would send a message to /dev/null if it was sent to a particular alias:
fooname: /dev/null
I have postfix set up with a default address for a particular domain in my /etc/postfix/virtual file:
@mydomain.com realuser
I have multiple domains mapped to this server. I've found that if I send a message to "fooname@mydomain.com, realuser@mydomain.com, fooname@otherdomain.com, realuser@otherdomain.com" I will receive the first, second, and fourth messages, but I won't receive the third.
The upshot is that entries in /etc/aliases don't seem to short circuit the email sending.
How do I send messages for particular aliases to /dev/null while still keeping the default alias?