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Dovecot 2.4 doveadm_worker_count corrupts tab-formatted output
by Philip Iezzi 25 Feb '26

25 Feb '26

Hi there On a Dovecot 2.4.2 (Debian Bookworm) server with over 1300 users, I am using the following config to retrieve quota usage information with doveadm: --------------------------------------- quota "User quota" { } mail_plugins = quota acl mail_log notify userdb sql { iterate_query = SELECT username AS user, CONCAT(quota, 'M') AS quota_storage_size FROM mailaccounts WHERE active = 1 query = \ SELECT '/var/vmail/%{user | domain}/%{user | username}' AS home, 'vmail' AS uid, 'vmail' AS gid, CONCAT(quota, 'M') AS quota_storage_size \ FROM mailaccounts \ WHERE username = '%{user}' AND (active = 1 OR transport_suspended = 0) } --------------------------------------- Initially, I had to run `doveadm quota recalc -A` to recalc quotas and populate the `count` quota driver which is enabled by default for "User quota". But still, it took roughly 20ms per single user or 15-20s for all users: $ time doveadm -f tab quota get -u demo(a)example.com real 0m0.020s $ time doveadm -f tab quota get -A real 0m16.800s Now, to greatly speed this up, I have introduced parallel processing: doveadm_worker_count = 4 Like this, `doveadm -f tab quota get -A` runs approx 10x faster, done in 1.5 - 2.5s But there is one major drawback which I assume to be a bug: # sane output without `doveadm_worker_count = 4` => always 6 fields demo(a)example.com User quota STORAGE 29 204800 0 demo(a)example.com User quota MESSAGE 1 - 0 # broken output with `doveadm_worker_count = 4` => sometimes 7 fields demo(a)example.com User quota STORAGE 29 2048 00 0 demo(a)example.com User quota MESSAGE 1 - 0 Somehow, the tab formatter does not play nicely together with parallel processing. On some output, the value gets split apart by an extra tab, e.g. '2024<TAB>00' in above example. Can you explain this corrupted data? Some kind of "output interleaving" seems to happen when running parallel workers. If I switch to json output (`doveadm -f json quota get -A`), this does not seem to happen and I always get valid JSON output, even with `doveadm_worker_count = 4`. Cheers, Philip

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Dovecot 2.4 LMTP socket for Postfix / Dovecot base_dir not created upon restart
by Philip Iezzi 24 Feb '26

24 Feb '26

Hi there, After over a week of Dovecot 2.3 -> 2.4 upgrade testing in various mailserver clones, I am now ready for the big picture. Thanks Aki for the Config Upgrader https://dovecot.org/upgrader/ which helped a lot! Tomorrow, I am planning to upgrade a larger mailserver in these 3 steps: 1) Debian Bullseye / Dovecot 2.3.21 => 2.4.1 2) Debian Bullseye => Bookworm / Dovecot 2.4.1 => 2.4.2 3) Debian Bookworm => Trixie Postfix needs to talk to Dovecot over LMTP, using the following in main.cf: virtual_transport = lmtp:unix:/run/dovecot/lmtp Now, while testing this in a full server clone, I stepped over my planned LMTP server setup: =============================================== service lmtp { unix_listener /run/dovecot/lmtp { mode = 0666 user = postfix group = postfix } } protocols = imap pop3 sieve lmtp =============================================== The socket needs to be owned by postfix:postfix for some (security) reasons, otherwise Postfix complains. That's why I cannot go with the default, as documented here: https://doc.dovecot.org/2.4.2/core/config/delivery/lmtp.html#lmtp-server > The UNIX listener on $base_dir/lmtp is enabled by default when protocols setting contains lmtp. But, when using an absolute path on unix_listener, upgrade step 2) Bullseye=>Bookworm breaks with: Processing triggers for dovecot-core (2:2.4.2-2+debian12) ... Job for dovecot.service failed because the control process exited with error code. (...) dovecot[34446]: master: Error: service(lmtp): Socket already exists: /var/run/dovecot/lmtp dovecot[34446]: master: Fatal: Failed to start listeners I then moved to `unix_listener lmtp`: service lmtp { unix_listener lmtp { mode = 0666 user = postfix group = postfix } } Bookworm upgrade (restarted from scratch with a fresh server clone) went through fine. But even after several dovecot.service restarts, the socket ended up in /run/lmtp without creating the /run/dovecot directory, and after a full system reboot, it was suddenly back where I have expected it: /run/dovecot/lmtp I never changed base_dir, which defaults to /var/run/dovecot/ So, here's my question: Is that really the recommended setup (using `inet_listener lmtp` instead of an absolute path) and how can I trust Dovecot to always create the socket in $base_dir/lmtp as documented? Are you guys aware of this issue or was it just me, a temporary hiccup on my just upgraded server? I just found this in mail.log: dovecot: master: Error: bind(/var/run/dovecot/lmtp) failed: No such file or directory dovecot: master: Error: service(lmtp): net_listen_unix(/var/run/dovecot/lmtp) failed: No such file or directory dovecot: master: Fatal: Failed to start listeners Again, this problem seems to have occurred both with `unix_listener /run/dovecot/lmtp` and `unix_listener lmtp` and only resolved after a full system reboot. Thanks, Philip

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Migrating a mailbox from v2.2 to v2.4, production server to pre-production server.
by Mike 23 Feb '26

23 Feb '26

I'm migrating a mailbox from dovecot v2.2 to v2.4. Not that it matters, I'm also changing from mbox to Maildir. As an initial test I used this command: sudo doveadm sync -1D -u theuser -m amailbox remote:theuser@destination.com I received this error: Error: doveadm: Unexpected or incomplete option: -U After changing the dsync_remote_cmd to: dsync_remote_cmd = ssh -l%{login} %{host} doveadm dsync-server -u%u I was able to transfer the mailbox without issue. Before changing it, the setting on the source server was: dsync_remote_cmd = ssh -l%{login} %{host} doveadm dsync-server -u%u -U I'm interested to discover what the -U was intended for since I couldn't find specific documentation to its use. I'll accept that it was a legacy thing and removing it won't cause any unintended consequences...but I do still have that curiosity about what it was for. Additionally, the subscription status doesn't seem to flow to the new server. When checking the source server with: doveconf -d | grep subscriptions doveconf -n | grep subscriptions No value is returned...So I'm wondering if I need to specifically set subscriptions = yes in the source server to make this happen properly. Maybe this is an artifact of using sync -1? Thanks for any insight you may provide. Mike

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Dovecot marking outgonig emails as unread
by stef204 23 Feb '26

23 Feb '26

Starting a few days ago, I have one email account where ALL outgoing emails are automatically marked as UNREAD. The message is sent, then copied to the "Sent" folder, and has status "unread". Then, a couple of minutes later, something happens where this message gets marked as UNREAD, without ANY interaction of client side. This occurs not matter the email client used, I have tried it with multiple email clients, both local and via web interface, the behavior does not change. This is via Dovevot on Cpanel. if I look at the [1]changelog, it is difficult to identify which changes could have triggered this as there seem to be changes impacting Dovecot almost with every update. I do not control the server myself, this is on a shared hosting plan; tech support has been willing to troubleshoot but is unable to locate the problem. This problem does NOT occur on other email accounts on the same domain, so it looks to me like some corruption or problem syncing flags perhaps? I am at a loss at the moment to fix this behavior. Any suggestions or ideas welcome. Thanks. References Visible links 1. https://docs.cpanel.net/changelogs/132-change-log/

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Localhost Dovecot server without ssl?
by Steve Litt 23 Feb '26

23 Feb '26

Hi all, I'd like your opinions to add to my own opinion. Bottom line question: If I trust everybody with physical access to my Daily Driver Desktop (DDD) computer, my Dovecot IMAP runs on my DDD, I access my Dovecot IMAP *exclusively* from my DDD, and I trust everybody with physical access to my DDD (that would be my wife), then if I serve out IMAP on localhost (127.0.0.1), am I being unduly risky using plain text auth (port 143)? Details: I use a Dovecot IMAP server, on my DDD, specifically to hold all my email messages. Therefore, I can use any IMAP aware email client, interchangeably, to view every email I've received since April 2001. People whose emails are held by their email clients are "locked in" to their email client unless they convert their email data. I can switch between Evolution and Claws-Mail, because one of the two is always doing something stupid. Bottom line: I use Dovecot IMAP exclusively to hold my emails and folders. Graphical description below: ISP ---> My --------> procmail --> Dovecot IMAP fetchmail Maildir | | V email <--- Dovecot client IMAP server For the time being, I don't need to access my Dovecot IMAP from any computer except my DDD, and therefore, I can serve Dovecot IMAP on 127.0.0.1. So here's my question. Assuming (and I know this is a big assumption) I'm not worried about somebody gaining physical possession of my DDD, is there any reason not to use plain text to access this server? Thanks, SteveT Steve Litt http://444domains.com

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Copies/duplicates of Dovecot indices
by Joseph Tam 23 Feb '26

23 Feb '26

In my setup, I put mail indices outside the user's mailbox locations (user mailboxs are NFS, indices stored local attached storage). I notice that sometimes, there are 2 sets of indices representing the same mailbox: one at top level, one underneath .imap/. (They usually appear in the latter.) For example, if I have the configuration (Dovcot version 3.2.21) mail_location = mbox:~/mail:INBOX=/nfs/mail/%n:INDEX=/cache/%n I see for a particular user [1] drwx------ 5 user group 512 Feb 22 21:56 /cache/user/box [2] drwxr-xr-x 5 user group 512 Feb 22 21:46 /cache/user/.imap/box cooresponding to their mailbox in ~user/mail/box. Each of these have the dovecot.* index files. If I delete [1], it comes back. The timestamps are close to each other so both sets are being used, possibly by different clients. Another quirky discovery is 2 /.imap/ folders beneath each other e.g. /cache/user/.imap/folder1/folder2/.imap/box/dovecot.index What determines which index pathname gets created or used? Joseph Tam <jtam.home(a)gmail.com>

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Panic in logs
by Kamil Jońca 22 Feb '26

22 Feb '26

Recently I found in my lda logs: 2025-12-30T07:55:14.717927+01:00 alfa dovecot: lda(kjonca): Error: Raw backtrace: #1 [unw_get_proc_name() failed: -10] -> #2 i_syslog_fatal_handler[0x7f99a2351430] -> #3 i_panic[0x7f99a226d453] -> #4 [unw_get_proc_name() failed: -10] -> #5 [unw_get_proc_name() failed: -10] -> #6 [unw_get_proc_name() failed: -10] -> #7 buffer_append[0x7f99a2345270] -> #8 dregex_code_match_groups[0x7f99a233f1a0] -> #9 [unw_get_proc_name() failed: -10] -> #10 [unw_get_proc_name() failed: -10] -> #11 sieve_match_value[0x7f99a117f770] -> #12 sieve_match[0x7f99a117fa30] -> #13 [unw_get_proc_name() failed: -10] -> #14 sieve_interpreter_continue[0x7f99a117e100] -> #15 sieve_multiscript_run[0x7f99a1190330] -> #16 [unw_get_proc_name() failed: -10] -> #17 mail_deliver[0x7f99a27e54a0] -> #18 main[0x55e371c555e0] -> #19 __libc_start_call_main[0x7f99a1e29f00] -> #20 __libc_start_main_alias_2[0x7f99a1e29fa0] -> #21 _start[0x55e371c566a0] And sadly it seems, that mail is missing (it was passed to pipe program to further processing) KJ -- http://wolnelektury.pl/wesprzyj/teraz/ When you go out to buy, don't show your silver.

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2.3 replication issue throwing errors
by Paul Kudla 22 Feb '26

22 Feb '26

shows same error on both servers Server 1 : # sync faye(a)scom.ca doveadm(faye(a)scom.ca)<90952><BJq9J2dHmGlIYwEA0dxyZQ>: Warning: Mailbox changes caused a desync. You may want to run dsync again: Remote lost mailbox GUID f982a82747469869ea0f0100cf58dcff (maybe it was just deleted?) Server 2: # sync faye(a)scom.ca doveadm(faye(a)scom.ca)<90952><BJq9J2dHmGlIYwEA0dxyZQ>: Warning: Mailbox changes caused a desync. You may want to run dsync again: Remote lost mailbox GUID f982a82747469869ea0f0100cf58dcff (maybe it was just deleted?) i am aware there is a mismatch on one of the servers but there does not seem to be a clear cut way to find the offending file to delete it or force a backwards sync ? How would i identify what GUID f982a82747469869ea0f0100cf58dcff means? same on both servers. doveadm force-resync -u faye(a)scom.ca '*' have tried reindex etc etc etc issue persists logs ?? mail18 02-20 06:45:24 {dovecot} [67632] (3014654310) doveadm(faye(a)scom.ca)<71073><hOl0ClRJmGmhFQEAz1jc/w>: Debug: open(/proc/self/stat) failed: No such file or directory mail18 02-20 06:45:24 {dovecot} [67632] (3014654311) doveadm(faye(a)scom.ca)<71073><hOl0ClRJmGmhFQEAz1jc/w>: Debug: open(/proc/self/io) failed: No such file or directory mail18 02-20 06:45:24 {dovecot} [67632] (3014654312) doveadm(faye(a)scom.ca)<71073><hOl0ClRJmGmhFQEAz1jc/w>: Debug: Namespace inbox: type=private, prefix=, sep=/, inbox=yes, hidden=no, list=yes, subscriptions=yes location=maildir:~/ any help would be appreciated -- Thanks - Paul Kudla (Manager SCOM.CA Internet Services Inc.) Have A Happy Friday AND Happy Sucessful 2026 ! Scom.ca Internet Services <http://www.scom.ca> 104-1009 Byron Street South Whitby, Ontario - Canada L1N 4S3 Toronto 416.642.7266 Main 1.866.411.7266 Fax 1.888.892.7266 Email paul(a)scom.ca

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How to declare port 143
by Steve Litt 20 Feb '26

20 Feb '26

Hi all, I have Dovecot 2.4.2 working (plain text only) on my Qemu virtual machine, with Claws-Mail able to work with all its files. However, I want to declare the Dovecot server as running on Port 143, and when I do, I dovecot -F throws the error message shown later in this message. If I comment out the explicit port declaration, it works fine, and I want to know why. To the best of my knowledge, my declaration of port 143 exactly matches your 2.4.2 documentation: The following is my attempt to tell Dovecot to serve *explicitly* at port 143: =============================================== # My Dovecot server will operate on Localhost listen = 127.0.0.1 service imap { inet_listener imap-login { port = 143 } # inet_listener imaps { # port = 993 # ssl = yes # } } =============================================== The following is the result: =============================================== [root@dovecotvoid ~]# dovecot -F doveconf: Fatal: Error in configuration file /etc/dovecot/dovecot.conf: duplicate listener: 143:127.0.0.1 [root@dovecotvoid ~]# =============================================== If I comment out the port = 143, it works. Why is it griping about a duplicate listener? At the bottom of this email is the entire dovecot.conf and the result of dovecot -n, and there are no sub-configuration files in conf.d : =============================================== # Start new configs with the latest Dovecot version numbers here: dovecot_config_version = 2.4.2 # Must be current version dovecot_storage_version = 2.4.2 # Must be current version or earlier # 2.3 is minimum # I only want imap protocols { imap = yes lmtp = no pop3 = no } # My Dovecot server will operate on Localhost listen = 127.0.0.1 service imap { inet_listener imap-login { port = 143 } # inet_listener imaps { # port = 993 # ssl = yes # } } # mail_home is only for virtual users # A virtual user is a user with no system account # I have no virtual users, so I've commented out mail_home. #mail_home = /srv/mail/%{user} # mail_driver is the storage format mail_driver = maildir # mail_path is location of top of storage data # WARNING: For troubleshooting be prepared to switch # to literal location of ~ mail_path = ~/mail/Maildir # In my case # mail_home is the home directory of the user identified as ~ # WARNING: system users have no ~ without it. mail_home = /home/slitt # You need a log you can locate # There might not be a log_path=/var/log/dovecot.log #mail_uid = slitt #mail_gid = slitt mail_uid = vmail mail_gid = vmail # By default first_valid_uid is 500. #If your vmail user's UID is smaller, # you need to modify this: #first_valid_uid = uid-number-of-vmail-user namespace inbox { inbox = yes separator = / } # Authenticate as system users: passdb pam { driver = pam #driver = passwd } userdb passwd { driver = passwd } #ssl_server_cert_file = /etc/dovecot/ssl-cert.pem #ssl_server_key_file = /etc/dovecot/ssl-key.pem =============================================== The following is the output of dovecot -n: =============================================== # 2.4.2 (0962ed2104): /etc/dovecot/dovecot.conf # OS: Linux 6.12.71_1 x86_64 # Hostname: dovecotvoid dovecot_config_version = 2.4.2 dovecot_storage_version = 2.4.2 listen = 127.0.0.1 log_path = /var/log/dovecot.log mail_driver = maildir mail_gid = vmail mail_home = /home/slitt mail_path = ~/mail/Maildir mail_uid = vmail protocols { imap = yes lmtp = no pop3 = no } service imap { inet_listener imap-login { port = 143 } } namespace inbox { inbox = yes separator = / } passdb pam { driver = pam } userdb passwd { driver = passwd } ===============================================

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How do you use doveadm fetch -S
by Steve Litt 20 Feb '26

20 Feb '26

Hi all, I have a working plain text 127.0.0.1:143 Dovecot 2.4.2 on my Qemu VM guest. The following command displays the Receive date, From and Subject for every email in my golugTech mailbox, exactly like the docs say it should: =================================================== doveadm fetch -u slitt "date.received hdr.from hdr.subject" mailbox golugTech =================================================== But when I add the -S in order to specify the 127.0.0.1 listener at port 143, it throws the following error: =================================================== [slitt@mydesk ~]$ cat junk.jnk [root@dovecotvoid dovecot]# doveadm fetch -S 127.0.0.1:143 -u slitt "date.received hdr.from hdr.subject" mailbox golugTech doveadm(slitt): Error: conn 127.0.0.1:143 (127.0.0.1:143): doveadm server sent invalid handshake: * OK Waiting for authentication process to respond.. doveadm(slitt): Error: cmd fetch: 127.0.0.1:143: Command fetch failed for slitt: Connection closed [root@dovecotvoid dovecot]# [slitt@mydesk~]$ =================================================== The docs say -S is to specify the socket_path, and it should be expressed as hostname:port. For hostname, besides 127.0.0.1, I tried localhost and dovecotvoid, the latter of which should not work because dovecotvoid is not 127.0.0.1, it's 10.0.2.15. The docs say "This allows an administrator to execute doveadm(1) mail commands through the given socket." So I guess finding the server isn't the purpose of socket_path. My plain text 143 Dovecot 2.4.2 IMAP works just fine without the -S. Is there ever a case where doveadm fetch would need to know the specific address and port of the dovecot IMAP server, and if so, how would I specify it? Thanks, SteveT Steve Litt http://444domains.com

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