Using lmtp to authenticate email users

[Jerry]

On Thu, 28 Mar 2019 05:22:37 -0700, Patrick Mahan via dovecot stated:

>FreeBSD 11.2
>Postfix 3.3.2
>Dovecot 2.3.4
>
>I am trying to use dovecot lmtp with postfix to verify authentication
>of incoming email and to avoid being a spam relay (an issue I was
>having using sendmail as my MTA).
>
>I am getting the following log message in /var/log/maillog:
>
>Mar 30 20:31:38 ns postfix/smtpd[40373]: NOQUEUE: reject: RCPT from
>mail-eopbgr750091.outbound.protection.outlook.com[40.107.75.91]: 450
>4.1.1 < mahan at mahan.org>: Recipient address rejected: unverified
>address: host ns.mahan.org[private/dovecot-lmtp] said: 550 5.1.1
><mahan at mahan.org> User doesn't exist: mahan at mahan.org (in reply to
>RCPT TO command); from=< pmahan at silver-peak.com> to=<mahan at mahan.org>
>proto=ESMTP helo=< NAM02-BL2-obe.outbound.protection.outlook.com>
>
>'mahan' does exist on ns.mahan.org.  So I am confused to why lmtp is
>failing to find this username.
>
>Thanks,
>
>Patrick
>

You probably shuld be asking this on the Postfix forum. Have you read
<http://www.postfix.org/ADDRESS_VERIFICATION_README.html>? You also
have "smtpd_reject_unlisted_recipient" options. You really need to post
the output of "postconf -nf" and perhaps "postconf -Mf".

-- 
Jerry