I am trying to utilize 'reject_unverified_recipient' selectively, so
that only addresses for domains which I host are verified
I might not be understanding your goals, but if you only want to verify
email accounts that the server is final destination for you don't want
to be using reject_unverified_recipient. You might be misunderstanding
what this feature is for.
http://www.postfix.org/ADDRESS_VERIFICATION_README.html
reject_unlisted_recipient is what postfix uses to check if the address
is valid for the accounts it accepts mail for.
The reject_unverified_recipient and reject_unverified_sender are for
checking if an email address hosted else where is valid. It causes
postfix to attempt to delivery a fake email to that account on another
server. I say fake in the sense that once it finds out that address is
legit it aborts the message and doesn't send an email.
A use case would be... when accepting email, to prevent spam, you could
check that the person claiming to be sending you that email is real. Not
a made up f...@spammer.com address. If postfix tries to fake deliver an
email to the f...@spammer.com address and it can't it would then reject
receiving an email from that address.
Postfix designers caution against using this feature as an everyday
every mail option as it has some draw backs which you read about on the
page linked above.
