"null route" messages to specific external recipient?

We have a custom application that sends notification to a hardcoded
email address external to our domain, with the sender being the address
of the user currently logged in.

This address is no longer valid, so each time a notification is sent, a
bounce is sent back to the user of the application indicating this.

This is a legacy application and do not have access to the source code.

Is there any way to simply "null route" messages sent to this
recipient, ie: notify@external-domain.com.

I have tried using the following in main.cf:

smtpd_recipient_restrictions = check_recipient_access
hash:/etc/postfix/blacklist_recipients, permit_mynetworks,
reject_unauth_destination

With blacklist_recipients containing:

notify@external-domain.com REJECT


but this still generates a bounce. I would like there to be no bounce
for this address. Other addresses for external-domain.com still need to
function though.

Thank you for any insight!

Try changing the "REJECT" to "DISCARD"

--
Greg

Thanks Greg. I have just tried this but get the following error in
maillog:

"warning: access table hash:/etc/postfix/blacklist_recipients: with
smtpd_proxy_filter specified, action DISCARD is unavailable"

I am new to postfix, I have just come from qmail, still getting my
bearing straight.

This system is setup with amavisd-new (funning clamav and spam
assassin) running as a proxy in front of postfix. Perhaps I need to do
my filtering within amavisd?

Could I somehow rewrite the recipient address to redirect to a local
"junk" account that gets cleared out periodically?