I discovered that my postfix/dovecot configuration isn't rejecting emails. If a person sends an email to an invalid email-address, it just drops it. I am fine with this behavior since I think it discourages spammers from mining emails (I have had some success). Recently a person I did not want to talk to emailed an address I cut off and didn't receive a response back. It would have saved me some problems if they knew to call me instead of sending 50+ emails. How would I configure Dovecot/postfix to send a message back to a sender of an email address and then limit this 1 per domain or unique email.
PSQL - backend if that matters