Trying to debug postfix 'unknown mail transport error'

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Trying to debug postfix 'unknown mail transport error'

Patrick Mahan

FreeBSD 11.2, Postfix 3.3.2, Dovecot 2.3.4

Random user verification failures are occurring and I am not sure why.

Here's an example -

From /var/log/maillog:

Failure:

Jan 21 12:20:41 ns postfix/smtpd[31736]: NOQUEUE: reject: RCPT from mta2.email.famousfootwear.com[136.147.183.86]: 450 4.1.1 <[hidden email]>: Recipient address rejected: unverified address: unknown mail transport error; from=<[hidden email]> to=<[hidden email]> proto=ESMTP helo=<mta2.email.famousfootwear.com>
....
Jan 21 12:20:41 ns dovecot: lmtp(31763): Connect from local
Jan 21 12:20:41 ns dovecot: lmtp(31763): Disconnect from local: Client has quit the connection (state=READY)

Success:

Jan 21 12:20:41 ns postfix/lmtp[31778]: 189C1A2DFB1: to=<[hidden email]>, relay=ns.mahan.org[private/dovecot-lmtp], delay=0, delays=0/0/0/0, dsn=2.1.5, status=deliverable (250 2.1.5 OK)

I am not sure why it sometimes fails.  Any help is appreciated.

My config (that I think are related)

Postfix mail transport:

root@ns:/usr/local/etc/dovecot # postconf -n | grep transport
mailbox_transport = lmtp:unix:private/dovecot-lmtp

Dovecot auth config

auth_cache_size = 10 M
auth_username_format = %Ln

service auth-worker {
  user = postfix
}

service auth {
  unix_listener /var/spool/postfix/private/auth {
    group = postfix
    mode = 0666
    user = postfix
  }
}

Dovecot lmtp config:

protocols = imap lmtp sieve

service lmtp {
  unix_listener /var/spool/postfix/private/dovecot-lmtp {
    group = postfix
    mode = 0666
    user = postfix
  }
}

protocol lmtp {
  mail_fsync = optimized
  mail_plugins = " sieve"
}

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Re: Trying to debug postfix 'unknown mail transport error'

Viktor Dukhovni
> On Jan 21, 2019, at 3:44 PM, Patrick Mahan <[hidden email]> wrote:
>
> Jan 21 12:20:41 ns postfix/smtpd[31736]: NOQUEUE: reject: RCPT from mta2.email.famousfootwear.com[136.147.183.86]: 450 4.1.1 <[hidden email]>: Recipient address rejected: unverified address: unknown mail transport error; from=<[hidden email]> to=<[hidden email]> proto=ESMTP helo=<mta2.email.famousfootwear.com>
> ....
> Jan 21 12:20:41 ns dovecot: lmtp(31763): Connect from local
> Jan 21 12:20:41 ns dovecot: lmtp(31763): Disconnect from local: Client has quit the connection (state=READY)

You have left out earlier logging by the Postfix lmtp(8) delivery agent that
details the "unknown mail transport error" in question.  The Dovecot LMTP
server logs are not especially informative in this case.

--
        Viktor.

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Re: Trying to debug postfix 'unknown mail transport error'

Wietse Venema
In reply to this post by Patrick Mahan
Patrick Mahan:

> FreeBSD 11.2, Postfix 3.3.2, Dovecot 2.3.4
>
> Random user verification failures are occurring and I am not sure why.
>
> Here's an example -
>
> >From /var/log/maillog:
>
> Failure:
>
> Jan 21 12:20:41 ns postfix/smtpd[31736]: NOQUEUE: reject: RCPT from
> mta2.email.famousfootwear.com[136.147.183.86]: 450 4.1.1 <[hidden email]>:
> Recipient address rejected: unverified address: unknown mail transport

http://www.postfix.org/DEBUG_README.html#logging

Look for obvious signs of trouble

Postfix logs all failed and successful deliveries to a logfile. The
file is usually called /var/log/maillog or /var/log/mail; the exact
pathname is defined in the /etc/syslog.conf file.

When Postfix does not receive or deliver mail, the first order of
business is to look for errors that prevent Postfix from working
properly:

    % egrep '(warning|error|fatal|panic):' /some/log/file | more

Note: the most important message is near the BEGINNING of the output.
Error messages that come later are less useful.
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Re: Trying to debug postfix 'unknown mail transport error'

Patrick Mahan
In reply to this post by Viktor Dukhovni
Viktor,

I didn't include it because I could not find it.  Which is, yes, confusing to me.  I looked for other failures from lmtp, but did not seen anything.

Thanks,

Patrick

On Mon, Jan 21, 2019 at 1:23 PM Viktor Dukhovni <[hidden email]> wrote:
> On Jan 21, 2019, at 3:44 PM, Patrick Mahan <[hidden email]> wrote:
>
> Jan 21 12:20:41 ns postfix/smtpd[31736]: NOQUEUE: reject: RCPT from mta2.email.famousfootwear.com[136.147.183.86]: 450 4.1.1 <[hidden email]>: Recipient address rejected: unverified address: unknown mail transport error; from=<[hidden email]> to=<[hidden email]> proto=ESMTP helo=<mta2.email.famousfootwear.com>
> ....
> Jan 21 12:20:41 ns dovecot: lmtp(31763): Connect from local
> Jan 21 12:20:41 ns dovecot: lmtp(31763): Disconnect from local: Client has quit the connection (state=READY)

You have left out earlier logging by the Postfix lmtp(8) delivery agent that
details the "unknown mail transport error" in question.  The Dovecot LMTP
server logs are not especially informative in this case.

--
        Viktor.