I was having a hard time stopping mail (read spam) beeing send to users like email@example.com
. (non existing mail accounts)
Guess what.. I've found a fix :-) (you probably knew this already)
After adding: local_recipient_maps = $alias_maps
to my /etc/postfix/main.cf
and doing a postfix reload
mail send to non existing users like uucp, mail and webmaster are now nicely rejected :-)
The attached message had PERMANENT fatal delivery errors!
After one or more unsuccessful delivery attempts the attached message has
been removed from the mail queue on this server. The number and frequency
of delivery attempts are determined by local configuration parameters.
YOUR MESSAGE WAS NOT DELIVERED TO ONE OR MORE RECIPIENTS!