December 2019 - dovecot

IMAP session hangs on 8k-long commands if COMPRESS=DEFLATE is enabled
by Guilhem Moulin 21 Apr '21

21 Apr '21

Hi there, Dovecot 2.3.7 appears to hang when the client sends a long command after enabling the IMAP COMPRESS extension [RFC 4978]. PoC script attached along with the doveconf(1) output. Without COMPRESS=DEFLATE, and with the default ‘imap_max_line_length’ value (64k) I'm able send commands up to 65539 bytes long (that's 3 bytes more than 2¹⁶, so maybe the leading tag and the trailing CRLF aren't counted), after which Dovecot rightfully replies with tagged BAD responses. $ COMPRESS=n /tmp/many-fetch.pl 65539 […] C: x UID FETCH 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,… [65539 bytes] S: x OK Fetch completed (0.005 + 0.001 + 0.004 secs). C: x UID FETCH 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,… [65540 bytes] S: x BAD Error in IMAP command UID FETCH: IMAP command line too large (0.001 + 0.001 secs). C: x UID FETCH 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,… [65541 bytes] S: x BAD Error in IMAP command UID FETCH: IMAP command line too large (0.001 + 0.001 secs). With COMPRESS=DEFLATE however, the server never sends anything back when the command size exceeds 8192 bytes: $ COMPRESS=y /tmp/many-fetch.pl 8192 […] S: x OK [READ-ONLY] Examine completed (0.001 + 0.000 secs). C: x UID FETCH 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,… [8191 bytes] S: x OK Fetch completed (0.001 + 0.000 secs). C: x UID FETCH 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,… [8192 bytes] S: x OK Fetch completed (0.001 + 0.000 secs). C: x UID FETCH 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,… [8193 bytes] [ _hangs until the server terminates the session for inactivity_ ] S: * BYE Disconnected for inactivity. strace(1) show that Dovecot didn't send the response, even though the server log indicates that it's able to fully read the command. Interestingly, when setting ‘imap_max_line_length’ to 4096, the server also hangs after receiving a command of size >4096 bytes (instead of replying with a tagged BAD response). $ COMPRESS=y /tmp/many-fetch.pl 4096 C: x UID FETCH 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,… [4095 bytes] S: x OK Fetch completed (0.001 + 0.000 secs). C: x UID FETCH 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,… [4096 bytes] S: x OK Fetch completed (0.001 + 0.000 secs). C: x UID FETCH 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,… [4097 bytes] [ _hangs until the server terminates the session for inactivity_ ] I'm also able to reproduce the buggy behavior against Dovecot versions found in other Debian releases. It's identical with 2.3.4 (Buster), the server also hang past 8192 bytes. 2.2.27 (Stretch) and 2.2.13 (Jessie) are able to send replies to 8k-long commands, but hang past 65536 bytes. For all 3 releases, without COMPRESS=DEFLATE Dovecot doesn't hang and rightfully sends tagged BAD responses to commands of size >65539 bytes. So while the hanging behavior appears to be a long-standing bug, the fact that's it's now hit at min($imap_max_line_length, 8192) instead of $imap_max_line_length seems to be a regression from somewhere between 2.2.27 and 2.3.4. Cheers, -- Guilhem.

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Dovecot SASL
by Jorge Bastos 22 Sep '20

22 Sep '20

Howdy, I know i've asked this before, but i think i got really no answer. I'd like to have dovecot SASL, to check AUTH against an SQL table, instead of dovecot SASL use the AUTH MECH for imap/pop3. I want this, to have the same behavior as I have now, where i use postfix with cyrus SASL on a different table (with the same login details), and when i have an user that his accounts was hacked for sending spam, i just block the send and allow the user to keep receiving emails, for example to warn him. Would this be possible? Dovecot SASL against a SQL table? Havent found much info about it, Thanks in advanced,

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LMTP-Process stays in RCPT TO state
by Pascal Christen 07 Sep '20

07 Sep '20

Hi We tried to update our Dovecot Director-Ring to 2.3 (latest version) and had one problem/bug. When we try to deliver an email from Exim to a receiving Dovecot (2.3 latest) via the LMTP-Proxy the LMTP process stays open forever and never closes. So after a few hours, we hit the LMPT-Process limit. The problem only exists if the receiving Dovecot reports "Quota exceeded (mailbox for user is full)" back to the Exim. If this is the case the state on the LMPT process stays at "lmtp: [_IP_ RCPT TO] (lmtp) and never closes. The TCP-Connection to the Exim is then in CLOSE_WAIT state on the Proxy. On the receiving Dovecot we set the "lmtp_rcpt_check_quota=yes" option. For me, it sounds similar to this bug: https://dovecot.org/list/dovecot/2018-January/110697.html but without the SEGFAULT which makes it harder to debug it. May you guys know why it doesn't change the state to IDLE or READY after reporting the quota issue or see something fishy in the commit above. If not I try to get a trace of the hanging process. Greetings Pascal

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How to backup maildir
by Robert Moskowitz 04 Sep '20

04 Sep '20

I have been thinking, and reading, on how to back up my mailserver. I have not found any approach that seems ready to use. I have run years without any backup, but would really like to have something in place. I figure I can attach a USB drive and backup to that, then from there rsync to something elsewhere. Further if that USB drive is a full mailserver image, I actually have a 'hot backup' where I only have to put the backup drive into a system and boot up at the last backup. But this means properly copying all of /home/vmail and probably /home/sieve plus the /var/lib/mysql Are there good tools that nicely does this? Or do I choose a time late at night (only I am sometimes in non-US timezones) to shut down all services and just use rsync? And stopping services itself is thought provoking. What if Dovecot, amavis, mysql, or whatelse is in the middle of writing out a mail file what happens to that file and restart. Just scary stuff and, in part, why I have never tackled this in the past. thanks for all feedback

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Rootless wiki page is not up to date?
by Marc Roos 20 Aug '20

20 Aug '20

If I run a docker image with the mesos containerizer and altering the dovecot config mentioned here[1] I think the root detection is incorrect because it looks like dovecot is still thinking it is root. I still get errors like: >> log(829825): Fatal: We couldn't drop root group privileges (wanted=10053(dovecot), gid=0(root), egid=0(root)) Why does it want to drop to root, if we are not even running as root? >> Error: service(ipc): chown(/var/dovecot/login/ipc-proxy, 91, 4294967295) failed: Operation not permitted Why does it want to chown, when it is not root? pop3-login: Fatal: setgid(101(dovenull)) failed with euid=10053(dovecot), gid=10053(dovecot), egid=10053(dovecot): Operation not permitted (This binary should probably be called with process group set to 101(dovenull) instead of 10053(dovecot)) [1] https://wiki.dovecot.org/HowTo/Rootless?action=edit&editor=text

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imap doesn't like my passwd
by James 31 Jul '20

31 Jul '20

I spent days on this problem. I have dovecot setup to use SSL and IMAP. I also have a pop account that I had no trouble getting working. Both use PAM authentication on Linux. openssl s_client -connect localhost:993 a login test_user test_secure_password The response I got back was: a BAD Invalid characters in atom I changed the password to "abc" and it worked. The secure password used to work but it was a different architecture (x86_64 I think). The current architecture is armhf. It may be different versions of the software too. Dovecot v2.1.7

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JMAP support
by Martynas Bendorius 23 Jun '20

23 Jun '20

Hello, Is there any ETA set for JMAP support? Thank you! >> On 11/27/2016 5:28 AM, Aki Tuomi <aki.tuomi at dovecot.fi> wrote: >> Hi! >> We are working on including JMAP support to Dovecot. At this moment I cannot give any promise for exact version, but hopefully it will be part of v2.3 >> >> Aki Tuomi >> Dovecot Oy -- Best regards, Martynas Bendorius

3 2

Warning: Failed to do incremental sync
by Laura Smith 08 Apr '20

08 Apr '20

Setup dovecot sync along the lines of (https://wiki2.dovecot.org/Replication) I am doing one way replication. The initial full replication happened without issue, but now I'm seeing these errors on the slave server: doveadm: Warning: /data/mail/foo/bar/Maildir/dovecot-uidlist: Duplicate file entry at line 26397: 1562173159.M215923P17350.mxp,S=2290,W=2339 (uid 143128 -> 143142) Warning: Failed to do incremental sync for mailbox Sent Messages, retry with a full sync (Modseq 1766 no longer in transaction log (highest=17617, last_common_uid=17559, nextuid=17560)) Warning: Failed to do incremental sync for mailbox INBOX, retry with a full sync (Modseq 2540 no longer in transaction log (highest=13870, last_common_uid=19912, nextuid=19913)) I guess dovecot automatically tries a full replication because eventually the messages get pushed and "sync failed" status changes from 'y' to '-'

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[Dovecot] Postfixadmin/MySQL/Dovecot 2 and quota
by Matt 01 Apr '20

01 Apr '20

Hi all, I'm setting up a new email server based on the softwares list below: * Postfix * Dovecot 2.0.9 * MySQL * Postfixadmin 2.3.6 My current problem is I'm unsure whether quota feature is well configured or not. In order to test and validate, I use Roundcubemail GUI which provides percentage of the space used by the mailbox (quota should be applied per mailbox). Here, my dovecot configuration: dovecot.conf: dict { quotadict = mysql:/etc/dovecot/dovecot-dict-quota.conf } dovecot-dict-quota.conf: connect = host=localhost dbname=postfix user=postfix password=postfix map { pattern = priv/quota/storage table = quota2 username_field = username value_field = bytes } map { pattern = priv/quota/messages table = quota2 username_field = username value_field = messages } dovecot-sql.conf.ext: driver = mysql connect = host=localhost dbname=postfix user=postfix password=postfix default_pass_scheme = PLAIN-MD5 password_query = SELECT username AS user, password, \ CONCAT('*:storage=', CAST(quota AS CHAR), 'b') AS quota_rule \ FROM mailbox WHERE username = '%u' AND active='1' user_query = SELECT maildir, 89 AS uid, 12 AS gid, \ concat('dict:storage=',floor(quota/1000),'::proxy::quotadict') AS quota, \ CONCAT('*:storage=', CAST(quota AS CHAR), 'b') AS quota_rule \ FROM mailbox WHERE username = '%u' AND active='1' conf.d/90-quota.conf: plugin { quota = dict:user::proxy::quotadict quota_rule2 = Trash:storage=+10%% } conf.d/20-imap.conf: protocol imap { mail_plugins = $mail_plugins imap_quota } When I check postfixadmin GUI, I can see that quota in realtime in quota2 table, no problem. But Roundcubemail cannot get this information and shows a unknown quota. If I add this line: quota_rule = *:storage=1G in conf.d/90-quota.conf file, it works, I mean roundcubemail gets and shows information (but not the one stored in db of course). I think I'm close to the right configuration but I need your help to complete this setup. Thank you in advance for your help. Best, Matt

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Dovecot 2.3 repo for CentOS 8.
by Reio Remma 15 Feb '20

15 Feb '20

Hello! Are there any plans for an official Dovecot repo for CentOS 8? Thanks, Reio

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