I'm trying to implement a solution for a noreply email address - devnull@example.com - to be sent to /dev/null on my MX server.
I have postfix setup using virtual domains which queries a remote mysql server running PostfixAdmin to administer the virtual domains.
In postfixadmin I have setup a real mailbox for devnull@example.com
I have also setup an alias - mailer@example.com - for the devnull@example.com mailbox.
Using the setup below mail is successfully being DISCARDed fine when email is addressed directly to devnull@example.com before the MX server attempts to deliver it via LMTP to my remote mail store.
But when the mail is sent to the alias - mailer@example.com - and includes orig_to (see below) the mail is NOT being DISCARDed.

Can anyone tell me the correct way to do this so it also catches mail when it has been aliased?

The regex below is "supposed" to catch ANY email accepted by this MX server addressed to any valid mailbox - devnull@anyvaliddomain.com

# cat /etc/postfix/devnull-discard
/^devnull@.*$/ DISCARD

# main.cf
smtpd_data_restrictions = check_recipient_access regexp:/etc/postfix/devnull-discard, reject_unauth_pipelining, reject_multi_recipient_bounce, permit

Any mail sent to - devnull@example.com - is successfully discarded:

Oct  1 20:50:26 mta-0 postfix/smtpd[27903]: DEB4FC096: discard: DATA from mail-pd0-f173.google.com[]: <devnull@example.com>: Recipient address triggers DISCARD action; from=<example@gmail.com> to=<devnull@example.com> proto=ESMTP helo=<mail-pd0-f173.google.com>

But any email message originally sent to - mailer@example.com - is not caught:

Oct  1 20:50:35 mta-0 postfix/lmtp[27909]: F3CDDC096: to=<devnull@example.com>, orig_to=<mailer@example.com>, relay=X.X.X.X[X.X.X.X]:2424, delay=1.1, delays=0.69/0.01/0.04/0.33, dsn=2.6.0, status=sent (250 2.6.0 <devnull@example.com> Message accepted for delivery)