Postfix: Custom Reject Message for Certain Email Adresses

Question

My websites sends mails to my users, and so far, my address is used as from, even if I didn't send that mail. I would like to change this to a noreply@... address, but since the users reply quite often to these emails, I would like to send them a helpful reject message. Mails to other non existing addresses should be unchanged.

How can I do so? I'm using Postfix 2.7.0 on Ubuntu 10.4.

Thanks!

Answer 1

Create a custom_replies map (i.e. /etc/postfix/custom_replies) with the following contents:

noreply@mydomain.com REJECT Like I said, NOREPLY

Run sudo postmap /etc/postfix/custom_replies.

Edit /etc/postfix/main.cf and put the following as the first check of the smtpd_recipient_restrictions:

check_recipient_access hash:/etc/postfix/custom_replies,

Then issue a sudo postfix reload.

Try sending email to noreply@mydomain.com:

$ telnet localhost 25
Trying ::1...
Trying 127.0.0.1...
Connected to localhost.
Escape character is '^]'.
220 mydomain.com ESMTP Postfix (Ubuntu)
HELO localhost
250 mydomain.com
MAIL FROM: <god@mydomain.com>
250 2.1.0 Ok
RCPT TO: <noreply@mydomain.com>
554 5.7.1 <noreply@mydomain.com>: Recipient address rejected: Like I said, NOREPLY
quit
221 2.0.0 Bye