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On Fri, 19 Jul 2013, Peer Heinlein wrote:
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".
Is the communication between postfix and Dovecot LMTP encrypted? If not, can you trace the LMTP transmission using something like wireshark or strace? So one get the impression of:
- how many connections uses postfix to communicate with LMTP
- which LMTP commands are transmitted in which order on which connection
Steffen Kaiser -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.11 (GNU/Linux)
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