Hello everyone,

I have following configurations (and more) at /etc/dovecot/local.conf in a "VirtualUserFlatFilesPostfix" setup :

[partial file content begins]

protocols = imap pop3 lmtp sieve

mail_location = maildir:~/data:INBOX=~/data/.INBOX

service lmtp {
    unix_listener /var/spool/postfix/private/dovecot-lmtp {
        user = vmail
        group = vmail
        mode = 0660
    }
}

protocol lmtp {
    postmaster_address = postmaster@example.net
    mail_plugins = $mail_plugins sieve
}

userdb {
    driver = passwd-file
    args = username_format=%u /srv/vmail/domains.d/%d/users.d/%n/etc/passwd
}

passdb {
    driver = passwd-file
    args = username_format=%u /srv/vmail/domains.d/%d/users.d/%n/etc/shadow.%Ls
}

service auth {
    unix_listener /var/spool/postfix/private/auth {
        user = postfix
        group = postfix
        mode = 0660
    }
}

[/partial file content ends]

Everyting works (IMAP mail is stored, IMAP/POP3 mail is retrieved, incoming SMTP mail from Postfix is delivered, Outgoing SMTP senders are authenticated from Postfix~SASL) BUT:

When incoming mail goes to a mailbox that does not exist, an error is logged by Dovecot, letter remains at Postfix queue, and no rejection message to sender (here host is mail.example.net):

[partial]$ cat /var/log/mail.log

2022-01-28T08:52:00.851751+01:00 correo postfix/smtpd[1853]: CFDA63A174B: client=mail.example.com[1.2.3.4]
2022-01-28T08:52:00.872248+01:00 correo postfix/cleanup[1881]: CFDA63A174B: message-id=<83c79ee1-6e2e-4e15-307e-17cdc7e2b814@example.com>
2022-01-28T08:52:00.884100+01:00 correo postfix/qmgr[1529]: CFDA63A174B: from=<johndoe@example.com>, size=854, nrcpt=1 (queue active)
2022-01-28T08:52:00.884507+01:00 correo postfix/smtpd[1853]: disconnect from mail.example.com[1.2.3.4] ehlo=2 starttls=1 mail=1 rcpt=1 data=1 quit=1 commands=7
2022-01-28T08:52:00.969275+01:00 correo postfix/lmtp[1882]: CFDA63A174B: to=<wronguser@example.net>, relay=mail.example.net[private/dovecot-lmtp], delay=0.43, delays=0.35/0.02/0.02/0.05, dsn=4.3.0, status=deferred (host mail.example.net[private/dovecot-lmtp] said: 451 4.3.0 <wronguser@example.net> Temporary internal error (in reply to RCPT TO command))

[partial]$ cat /var/log/dovecot.log

2022-01-28 08:52:00 lmtp(1883): Info: Connect from local
2022-01-28 08:52:00 auth: Error: passwd-file(wronguser@example.net): stat(/srv/vmail/domains.d/example.net/users.d/wronguser/etc/passwd) failed: Address family not supported by protocol
2022-01-28 08:52:00 lmtp(wronguser@example.net)<1883><xbrsNqCg82FbBwAAzZSvjA>: Error: user wronguser@example.net: Auth USER lookup failed
2022-01-28 08:52:00 lmtp(1883): Error: Failed to lookup user wronguser@example.net: Internal error occurred. Refer to server log for more information.
2022-01-28 08:52:00 lmtp(1883): Info: Disconnect from local: Client has quit the connection (state=READY)

Thank you for any help in debugging configuration or suggestion to enhance Postfix/Dovecot parameters.

Postfix 3.4

Dovecot 2.3

-- 

Narcis Garcia

__________
I'm using this dedicated address because personal addresses aren't masked enough at this mail public archive. Public archive administrator should fix this against automated addresses collectors.