smtpd_recipient_restrictions doesn't work as expected?

[wsan...@iparadigms.com]

We have an outgoing mail replay that sends a few hundred thousand or so mails a day from our apps (not humans) to our customers with a From: and Error_To: address of <nor...@turnitin.com>. Several hundred of these per day bounce back, for various reasons. In addition, this outgoing relay is in our iparadigms.com domain, and turnitin.com is in another; therefore from this relay's point of view turnitin.com is a "foreign" domain. The MX's for turnitin.com point to Google where we host our mail, so these bounce messages end up getting sent to Google and rate limited, so they pile up on this mail relay.

I would like to just have our outgoing relay discard all the bounces it gets that are destined for nor...@turnitin.com. I have tried setting smtpd_recipient_restrictions to this:

smtpd_recipient_restrictions = check_recipient_access hash:/etc/postfix/discard-noreply, permit_mynetworks, reject_unauth_destination

and the contents of /etc/postfix/discard-noreply are:

nor...@turnitin.com DISCARD discarded
nor...@iparadigms.com DISCARD discarded

(I was unable to get REJECT or HOLD to work either.)

This seems to have no effect. As I understand it smtpd_recipient_restrictions is supposed to take action on the RCPT TO address, which in this case is nor...@turnitin.com:

<nor...@turnitin.com>: host alt2.aspmx.l.google.com[173.194.219.26] said: 450-4.2.1 The user you are trying to contact is receiving mail too quickly. 450-4.2.1 Please resend your message at a later time. If the user is able to 450-4.2.1 receive mail at that time, your message will be delivered. For more 450-4.2.1 information, please visit 450 4.2.1 https://support.google.com/mail/answer/6592 s81si2978737ywc.216 - gsmtp (in reply to RCPT TO command)

Is this the way smtpd_recipient_restrictions is supposed to work?

The other alternative is to just discard all bounce processing. This will work for us, since this relay only handles automated mail from apps. But I'd prefer for smtpd_recipient_restrictions or some other feature to handle it.

Thanks in advance -wsanders