LMTP proxy does not pass RCPT TO: ... 5xx response back
Hello,
I'm using dovecot 2.2.9 and a director/backend setup. On the director I've the LMTP in proxy mode, mapping the users to one of the backends.
The backends to quota check and return the OverQuota message already at RCPT TO time.
Here is what I typed, connected to the director
Connection to director1 2525 port [tcp/*] succeeded!
220 director1.rz.hs-example.de Dovecot (Ubuntu) ready.
LHLO mailhub1.rz.hs-example.de
250-director1.rz.hs-example.de
250-8BITMIME
250-ENHANCEDSTATUSCODES
250 PIPELINING
MAIL FROM:<hs@schlittermann.de>
250 2.1.0 OK
RCPT TO:<heiko@hs-example.de>
250 2.1.5 OKAnd here is, what TCPDUMP sees (cut for clarity):
00:22:23.029251 IP6 2001:638:914:f33::5:1.59466 > 2001:638:914:f33::5:ff.2525: Flags [S],
00:22:23.029376 IP6 2001:638:914:f33::5:ff.2525 > 2001:638:914:f33::5:1.59466: Flags [S.],
00:22:23.029660 IP6 2001:638:914:f33::5:1.59466 > 2001:638:914:f33::5:ff.2525: Flags [.],
00:22:23.051436 IP6 2001:638:914:f33::5:ff.2525 > 2001:638:914:f33::5:1.59466: Flags [P.],
.7i`.7jN220 backend1.rz.hs-example.de Dovecot (Ubuntu) ready.
00:22:23.051805 IP6 2001:638:914:f33::5:1.59466 > 2001:638:914:f33::5:ff.2525: Flags [.],
00:22:23.052017 IP6 2001:638:914:f33::5:1.59466 > 2001:638:914:f33::5:ff.2525: Flags [P.],
.7jT.7i`LHLO director1.rz.hs-example.de
00:22:23.052034 IP6 2001:638:914:f33::5:ff.2525 > 2001:638:914:f33::5:1.59466: Flags [.],
00:22:23.052114 IP6 2001:638:914:f33::5:ff.2525 > 2001:638:914:f33::5:1.59466: Flags [P.],
.7ia.7jT250-backend1.rz.hs-example.de
250-XCLIENT ADDR PORT TTL TIMEOUT
250-8BITMIME
250-ENHANCEDSTATUSCODES
250 PIPELINING
00:22:23.052476 IP6 2001:638:914:f33::5:1.59466 > 2001:638:914:f33::5:ff.2525: Flags [P.],
0EH....d...... ..3........ ..8 ..3.........J .....
.7jT.7iaXCLIENT ADDR=2001:638:914:f33::7:1 PORT=60574 TTL=4 TIMEOUT=30
00:22:23.052540 IP6 2001:638:914:f33::5:ff.2525 > 2001:638:914:f33::5:1.59466: Flags [P.],
0EH...E....~e.....3........ ..8 ..3........ ..J
.7ia.7jT220 backend1.rz.hs-example.de Dovecot (Ubuntu) ready.
00:22:23.052815 IP6 2001:638:914:f33::5:1.59466 > 2001:638:914:f33::5:ff.2525: Flags [P.],
0E.....s...... ..3........ ..8 ..3.........J ....E
.7jT.7iaLHLO director1.rz.hs-example.de
00:22:23.052870 IP6 2001:638:914:f33::5:ff.2525 > 2001:638:914:f33::5:1.59466: Flags [P.],
0E....h....~......3........ ..8 ..3........ ..J
.7ia.7jT250-backend1.rz.hs-example.de
250-8BITMIME
250-ENHANCEDSTATUSCODES
250 PIPELINING
00:22:23.053120 IP6 2001:638:914:f33::5:1.59466 > 2001:638:914:f33::5:ff.2525: Flags [P.],
0E.....qJ..... ..3........ ..8 ..3.........J ....h
.7jT.7iaMAIL FROM:<hs@schlittermann.de>
RCPT TO:<heiko@hs-example.de>
00:22:23.091824 IP6 2001:638:914:f33::5:ff.2525 > 2001:638:914:f33::5:1.59466: Flags [.],
0E.........~,.....3........ ..8 ..3........ ..J
.7ik.7jT
00:22:23.119918 IP6 2001:638:914:f33::5:ff.2525 > 2001:638:914:f33::5:1.59466: Flags [P.],
0E.........~......3........ ..8 ..3........ ..J.7ir.7jT250 2.1.0 OK
552 5.2.2 heiko@hs-example.de Quota exceeded (mailbox for user is full)
00:22:23.158836 IP6 2001:638:914:f33::5:1.59466 > 2001:638:914:f33::5:ff.2525: Flags [.], 0F4....j...... ..3........ ..8 ..3.........J ..... .7jo.7ir 00:27:23.029008 IP6 2001:638:914:f33::5:1.59466 > 2001:638:914:f33::5:ff.2525: Flags [F.], 0F4....E...... ..3........ ..8 ..3.........J .....
It looks as if the backend tells the director/proxy about the full mailbox (552 5.2.2 heiko@hs-example.de Quota exceeded (mailbox for user is full)) already before the DATA phase starts, right as the response to the RCPT TO.
But the proxy seems to ignore it… Any suggestion?
Best regards from Dresden/Germany
Viele Grüße aus Dresden
Heiko Schlittermann-- SCHLITTERMANN.de ---------------------------- internet & unix support - Heiko Schlittermann, Dipl.-Ing. (TU) - {fon,fax}: +49.351.802998{1,3} - gnupg encrypted messages are welcome --------------- key ID: F69376CE - ! key id 7CBF764A and 972EAC9F are revoked since 2015-01 ------------ -
On 12 Feb 2016, at 01:37, Heiko Schlittermann hs@schlittermann.de wrote:
Hello,
I'm using dovecot 2.2.9 and a director/backend setup. On the director I've the LMTP in proxy mode, mapping the users to one of the backends.
The backends to quota check and return the OverQuota message already at RCPT TO time.
Here is what I typed, connected to the director
Connection to director1 2525 port [tcp/*] succeeded! 220 director1.rz.hs-example.de Dovecot (Ubuntu) ready. LHLO mailhub1.rz.hs-example.de 250-director1.rz.hs-example.de 250-8BITMIME 250-ENHANCEDSTATUSCODES 250 PIPELINING MAIL FROM:hs@schlittermann.de 250 2.1.0 OK RCPT TO:heiko@hs-example.de 250 2.1.5 OK
..
It looks as if the backend tells the director/proxy about the full mailbox (552 5.2.2 heiko@hs-example.de Quota exceeded (mailbox for user is full)) already before the DATA phase starts, right as the response to the RCPT TO.
But the proxy seems to ignore it…
Right.. RCPT TO in proxy answers immediately when it has verified that the user exists. It doesn't wait until it has connected to the backend and sent RCPT TO there. I'm also not entirely sure how good of an idea that is if it would, since at least without pipelining it would slow down all the LMTP operations when there are multiple recipients. But then again, if pipelining is used it wouldn't matter, at least in theory. It would require some more coding though.
The way it's commonly done in larger environments is that the over-quota is already checked by the MTA and have it fail the RCPT TO. You can have Dovecot update the over-quota flags via quota-warning scripts (and quota_over_script) in whatever way and have the MTA look that up. Then in Dovecot LMTP you could simply disable quota checks.
Hi Timo,
sorry for the delay, but many thanks for your answer (I was busy with the current Exim release).
Timo Sirainen tss@iki.fi (So 21 Feb 2016 02:57:55 CET): …
Right.. RCPT TO in proxy answers immediately when it has verified that the user exists. It doesn't wait until it has connected to the backend and sent RCPT TO there. I'm also not entirely sure how good of an idea that is if it would, since at least without pipelining it would slow down all the LMTP operations when there are multiple recipients. But then again, if pipelining is used it wouldn't matter, at least in theory. It would require some more coding though.
The way it's commonly done in larger environments is that the over-quota is already checked by the MTA and have it fail the RCPT TO. You can have Dovecot update the over-quota flags via quota-warning scripts (and quota_over_script) in whatever way and have the MTA look that up. Then in Dovecot LMTP you could simply disable quota checks.
Yes, that's the way we've to go now. But getting as much as possible information about the deliverability of a message by standard means would be good. And using the RCPT TO response would not need any magic mechanisms on the MTA side. We could use recipient verification via callouts (as we do to check the existence of the recipient, w/o the need to do some LDAP lookups).
Best regards from Dresden/Germany
Viele Grüße aus Dresden
Heiko Schlittermann-- SCHLITTERMANN.de ---------------------------- internet & unix support - Heiko Schlittermann, Dipl.-Ing. (TU) - {fon,fax}: +49.351.802998{1,3} - gnupg encrypted messages are welcome --------------- key ID: F69376CE - ! key id 7CBF764A and 972EAC9F are revoked since 2015-01 ------------ -
Hi,
Timo Sirainen tss@iki.fi (So 21 Feb 2016 02:57:55 CET):
The way it's commonly done in larger environments is that the over-quota is already checked by the MTA and have it fail the RCPT TO. You can have Dovecot update the over-quota flags via quota-warning scripts (and quota_over_script) in whatever way and have the MTA look that up. Then in Dovecot LMTP you could simply disable quota checks.
The over-quota flag isn't supported on 2.2.9 (which is what Ubuntu 14.04 has).
I tried the quota-status plugin. But it seems, this plugin tries to read the maildir directly. Doesn't help. Since I have a director/backend setup.
Can't quota-status use the same interface doveadm quota uses? Unfortunenatly I didn't find further documentation, except the source itself.
Best regards from Dresden/Germany
Viele Grüße aus Dresden
Heiko Schlittermann-- SCHLITTERMANN.de ---------------------------- internet & unix support - Heiko Schlittermann, Dipl.-Ing. (TU) - {fon,fax}: +49.351.802998{1,3} - gnupg encrypted messages are welcome --------------- key ID: F69376CE - ! key id 7CBF764A and 972EAC9F are revoked since 2015-01 ------------ -
participants (2)
-
Heiko Schlittermann
-
Timo Sirainen