I have some qmail aliases which no longer receive useful information — just spam. To send them to a black hole, I merely created a /etc/qmail/alias/.qmail-devnull file which contains:
| cat /dev/null
Next I added a new alias for the extension email address. For example, suppose ‘email@example.com’ is the address we wish to black hole. In /etc/qmail/users/assign I add:
UID and GID correspond to the ids for user ‘me’. Once I executed ‘qmail-newu’ as root all subsequent email to firstname.lastname@example.org went to the bit bucket.
UPDATE:This didn’t actually work….