[Dovecot] mails delivered to the wrong user when using lmtp_proxy and reject_unverified_recipient

[Charles Marcus]

doveconf -n and postconf -n output might shed some light?

On 2013-07-19 11:11 AM, Peer Heinlein <p.heinlein at heinlein-support.de> 
wrote:
> Hi,
>
> looks like we detected a serious bug in dovecot's lmtp proxying where
> e-mails are delivered to the wrong user.
>
> The setup is:
>
> *) Dovecot is configured with "lmtp_proxy=yes"
>
> # Support proxying to other LMTP/SMTP servers by performing passdb lookups.
> lmtp_proxy = yes
>
> *) Postfix uses "dynamic recipient verification", so Postfix starts
> sending a (verify) mail by LMTP to dovecot, but quits the lmtp-session
> right after the RCPT TO:. No DATA-stage is reached in the protocol and
> no real e-mail is sent. But Postfix had a LMTP-connection for "user1".
>
> *) Just some seconds later a "real" e-mail to "user2" has to be
> delivered to dovecot by LMTP. But Dovecot will deliver this mail to the
> wrong "user1" instead of "user2". Looks like dovecot re-uses the (still
> opened?) lmtp-proxy-connection from "user1" to deliver an e-mail to "user2".
>
> Have a log at the protocol:
>
> 1) There's a verify call to user1 from Postfix:
>
> Jul 19 13:49:49 mailms postfix/lmtp[9842]: DE653280C51:
> to=<user1 at example.com>, relay=localhost[127.0.0.1]:24, conn_use=2,
> delay=120, delays=117/0.45/0/2.5, dsn=2.1.5, status=deliverable (250
> 2.1.5 OK)
>
> 2) Just five seconds later the e-mail to user2 (see Postfix' point of
> view in the last line) is delivered to user2 (see result from Dovecot in
> the last line):
>
> Jul 19 13:50:04 mailms dovecot: lmtp(10965, kraemer): save: box=INBOX,
> uid=49880, msgid=<59798276-E5D1-4053-A570-9901B731DF5D at example.come>,
> size=11020
> Jul 19 13:50:04 mailms dovecot: lmtp(10965, kraemer):
> 1zTeKrMn6VHVKgAAhyqEuA:
> msgid=<59798276-E5D1-4053-A570-9901B731DF5D at example.com>: saved mail to
> INBOX
> Jul 19 13:50:04 mailms postfix/lmtp[10953]: C25FC280BE5:
> to=<user2 at example.com>, relay=localhost[127.0.0.1]:24, conn_use=19,
> delay=116, delays=115/0.53/0/0.33, dsn=2.0.0, status=sent (250 2.0.0
> <user2> 1zTeKrMn6VHVKgAAhyqEuA Saved)
>
>
> Same with user3 and user4:
>
> Jul 19 14:47:53 mailms postfix/lmtp[10845]: C389A2809D7:
> to=<user3 at example.com>, relay=localhost[127.0.0.1]:24, delay=4.7,
> delays=3.7/0.87/0/0.19, dsn=2.1.5, status=deliverable (250 2.1.5 OK)
> Jul 19 14:47:55 mailms dovecot: lmtp(26546, fs211113): save: box=INBOX,
> uid=8504, msgid=<928729810.113.1374238063381 at example.com>, size=233151
> Jul 19 14:47:55 mailms dovecot: lmtp(26546, fs211113):
> MbMvI2816VGyZwAAhyqEuA: msgid=<928729810.113.1374238063381 at example.com>:
> saved mail to INBOX
> Jul 19 14:47:55 mailms postfix/lmtp[22524]: 6F0D2280A6E:
> to=<user4 at example.com>, relay=localhost[127.0.0.1]:24, conn_use=2,
> delay=10, delays=8.4/1/0/0.8, dsn=2.0.0, status=sent (250 2.0.0 <user3>
> MbMvI2816VGyZwAAhyqEuA Saved)
>
>
>
> The user itself is quite normal in the user database (but has a
> mailhost=127.0.0.1 set):
>
> root at mailms:/etc/dovecot/conf.d# doveadm user user2 at example.com
> userdb: user2 at example.com
>    uid       : 5000
>    gid       : 5000
>    home      : /srv/mail/user2
>
> root at mailms:/etc/dovecot/conf.d# doveadm auth user2 at example.com
> Password:
> passdb: user2 at example.com auth failed
> extra fields:
>    user=user2
>
> Peer
>
>


-- 

Best regards,

Charles Marcus
I.T. Director
Media Brokers International, Inc.
678.514.6224 | 678.514.6299 fax