November 2025 - dovecot

[Dovecot] batch convert mbox to maildir
by Netlink Tech 18 May '26

18 May '26

Hello, I have used mb2md for an individual user like this: su ~username cd ~ ./mb2md -m This converted /var/spool/mail/username mbox to /home/users/username/Maildir just as I expected. To convert 100s of users the same way would be a chore (su as each user for permissions, etc.). Is there a way to batch process all /var/spool/mail/$USER to /home/users/$USER/Maildir with the correct permissions/file owners for each user?

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mbox to maildir migration, same server?
by kjohnson＠eclypse.org 25 Apr '26

25 Apr '26

What is the recommended procedure to migrate from mbox to maildir on a server already running dovecot? Ideally, this procedure would convert messages in an existing mbox INBOX and in ~/mail mboxes (as defined in my dovecot configuration) to storage in a ~/Maildir. Some of the INBOXs are rather large -- 100's of MB (one of the reasons for migrating). What I have tried has not worked for me. Below, I describe what I tried, how I tested before I tried, what went wrong, and the current setup (pre-migration). What I tried: ============= stop exim4 service dovecot stop Make dovecot listen only locally, not to external connections. /etc/dovecot/local.conf protocol imap { listen = 127.0.0.1:143 ssl_listen = 127.0.0.1:993 } protocol pop3 { listen = 127.0.0.1:110 ssl_listen = 127.0.0.1:995 } Modify dovecot configuration for maildir: Watch capitalization! #in 10-mail.conf: mail_location = maildir:/home/%u/Maildir namespace inbox { separator = / } dovecot -n, to confirm results and perform limited syntax checking. service dovecot start for each user, in a bash script: dsync -v -u "$U" mirror "mbox:/home/$U/mail:INBOX=/var/mail/$U" (if the conversion worked for all users, then reconfigure exim to use maildir and restart it; reconfigure dovecot to listen to external interfaces and restart.) How I tested: ============= Before trying this on the real server, I set up a matching (same versions of Debian, Exim, and Dovecot) VM using mbox, with a couple of accounts. One using POP3, one using IMAP. The IMAP account was accessed from Claws and from Outlook. The test accounts had perhaps a dozen messages on the server. I tried the conversion procedure, and everything I tried worked flawlessly. (Yes, next time I will move some real inbox files from the live server). What went wrong: ================ I encountered two types of problems here. The first was several dsync warnings (username changed): dsync(example): Warning: Mailbox changes caused a desync. You may want to run dsync again: Remote lost mailbox GUID 21bfa11a81f11763ac150000d09efc50 (maybe it was just deleted?) As I understand it, this can result in some or all messages being downloaded again by clients. My understanding may be wrong. I also don't understand how the mailbox could have changed -- exim4 was stopped, dovecot is only listening on 127.0.0.1, and I am the only user who uses a local mail client on that system, and this was not my account. The second problem I encountered seems to match Debian Bug report logs - #1011238. In part of the discussion of that report, the reporter mentions adding -1 to the command, as shown: dsync -v -u "$U" mirror -1 "mbox:/home/$U/mail:INBOX=/var/mail/$U" While this seemed to eliminate the dsync panic of #1011238, as far as I can tell, no old messages were actually moved from the old mbox files to the new maildirs. At that point I restored the backup mbox files and undid the changes to dovecot and exim4. Current setup: ============== Debian 11.4 Exim 4.94.2-7 dovecot 1:2.3.13+dfsg1-2 The current setup with Dovecot was a successful migration from IMAP-UW in December 2020. Output from dovecot -n (the list of trusted networks has been removed) # 2.3.13 (89f716dc2): /etc/dovecot/dovecot.conf # Pigeonhole version 0.5.13 (cdd19fe3) # OS: Linux 5.10.0-16-686-pae i686 Debian 11.4 # Hostname: localhost auth_verbose = yes mail_location = mbox:~/mail:INBOX=/var/mail/%u mail_privileged_group = mail namespace inbox { inbox = yes location = mailbox Drafts { special_use = \Drafts } mailbox Junk { special_use = \Junk } mailbox Sent { special_use = \Sent } mailbox "Sent Messages" { special_use = \Sent } mailbox Trash { special_use = \Trash } prefix = } passdb { driver = pam } pop3_uidl_format = %08Xv%08Xu protocols = " imap pop3" ssl_cert = </etc/dovecot/dovecot.pem ssl_client_ca_dir = /etc/ssl/certs ssl_dh = # hidden, use -P to show it ssl_key = # hidden, use -P to show it userdb { driver = passwd } Thank you to anyone who read this far. Ken

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doveadm batch crash
by Jonathan Casiot 13 Apr '26

13 Apr '26

Hi I'm having an issue with doveadm batch - the following command always crashes: doveadm batch : mailbox status all inbox Whereas the following work as expected: doveadm mailbox status all inbox doveadm batch : mailbox list Any assistance gratefully received. Debug output from the crash: Debug: Loading modules from directory: /usr/lib64/dovecot Debug: Module loaded: /usr/lib64/dovecot/lib01_acl_plugin.so Debug: Module loaded: /usr/lib64/dovecot/lib10_mail_crypt_plugin.so Debug: Module loaded: /usr/lib64/dovecot/lib90_stats_plugin.so Debug: Loading modules from directory: /usr/lib64/dovecot/doveadm Debug: Module loaded: /usr/lib64/dovecot/doveadm/lib10_doveadm_acl_plugin.so Debug: Skipping module doveadm_expire_plugin, because dlopen() failed: /usr/lib64/dovecot/doveadm/lib10_doveadm_expire_plugin.so: undefined symbol: expire_set_deinit (this is usually intentional, so just ignore this message) Debug: Skipping module doveadm_quota_plugin, because dlopen() failed: /usr/lib64/dovecot/doveadm/lib10_doveadm_quota_plugin.so: undefined symbol: quota_user_module (this is usually intentional, so just ignore this message) Debug: Skipping module doveadm_fts_lucene_plugin, because dlopen() failed: /usr/lib64/dovecot/doveadm/lib20_doveadm_fts_lucene_plugin.so: undefined symbol: lucene_index_iter_deinit (this is usually intentional, so just ignore this message) Debug: Skipping module doveadm_fts_plugin, because dlopen() failed: /usr/lib64/dovecot/doveadm/lib20_doveadm_fts_plugin.so: undefined symbol: fts_user_get_language_list (this is usually intentional, so just ignore this message) Debug: Module loaded: /usr/lib64/dovecot/doveadm/libdoveadm_mail_crypt_plugin.so doveadm(jc): Debug: Effective uid=1001, gid=100, home=/home/jc doveadm(jc): Debug: acl: No acl_shared_dict setting - shared mailbox listing is disabled doveadm(jc): Debug: mail_crypt_plugin: mail_crypt_curve setting missing - generating EC keys disabled doveadm(jc): Debug: Namespace inbox: type=private, prefix=, sep=., inbox=yes, hidden=no, list=yes, subscriptions=yes location=mdbox:~/mdbox:ALT=~/Archive/tape/mdbox doveadm(jc): Debug: fs: root=/home/jc/mdbox, index=, indexpvt=, control=, inbox=, alt=/home/jc/Archive/tape/mdbox doveadm(jc): Debug: acl: initializing backend with data: vfile doveadm(jc): Debug: acl: acl username = jc doveadm(jc): Debug: acl: owner = 1 doveadm(jc): Debug: acl vfile: Global ACLs disabled doveadm(jc): Panic: file mail-storage.c: line 875 (mailbox_set_reason): assertion failed: (reason != NULL) doveadm(jc): Error: Raw backtrace: /usr/lib64/dovecot/libdovecot.so.0(+0xa0e9e) [0x7fc993023e9e] -> /usr/lib64/dovecot/libdovecot.so.0(default_fatal_handler+0x2a) [0x7fc993023f0a] -> /usr/lib64/dovecot/libdovecot.so.0(i_fatal+0) [0x7fc992fb3c97] -> /usr/lib64/dovecot/libdovecot-storage.so.0(+0x49856) [0x7fc993301856] -> /usr/bin/doveadm(+0x348e2) [0x5631dbb5f8e2] -> /usr/bin/doveadm(+0x2e1ad) [0x5631dbb591ad] -> /usr/bin/doveadm(+0x2bd2c) [0x5631dbb56d2c] -> /usr/bin/doveadm(+0x2c92a) [0x5631dbb5792a] -> /usr/bin/doveadm(doveadm_mail_try_run+0x215) [0x5631dbb58285] -> /usr/bin/doveadm(main+0x46a) [0x5631dbb473fa] -> /lib64/libc.so.6(__libc_start_main+0xf5) [0x7fc992bd83d5] -> /usr/bin/doveadm(+0x1c565) [0x5631dbb47565] Aborted (core dumped) And doveconf -n output: # 2.2.36 (1f10bfa63): /etc/dovecot/dovecot.conf # OS: Linux 3.10.0-957.1.3.el7.x86_64 x86_64 CentOS Linux release 7.6.1810 (Core) # Hostname: ### redacted ### first_valid_gid = 100 first_valid_uid = 1000 last_valid_gid = 100 last_valid_uid = 1999 listen = * login_greeting = IMAP ready login_log_format_elements = user=<%u> method=%m rip=%r lip=%l mpid=%e session=<%{session}> %k mail_attribute_dict = file:%h/mdbox/dovecot-attributes mail_location = mdbox:~/mdbox:ALT=~/Archive/tape/mdbox mail_plugins = acl stats mail_crypt mailbox_list_index = yes mdbox_rotate_size = 16 M namespace inbox { inbox = yes location = mailbox Drafts { special_use = \Drafts } mailbox Junk { special_use = \Junk } mailbox Sent { special_use = \Sent } mailbox "Sent Messages" { special_use = \Sent } mailbox Trash { special_use = \Trash } prefix = separator = . } passdb { driver = pam } plugin { acl = vfile mail_crypt_global_private_key = <### redacted ### mail_crypt_global_public_key = <### redacted ### mail_crypt_save_version = 2 stats_memory_limit = 16 M stats_refresh = 30 secs stats_track_cmds = yes } postmaster_address = ### redacted ### protocols = imap service auth { unix_listener /var/spool/postfix/private/auth { group = postfix mode = 0660 user = postfix } } service imap-login { process_limit = 200 process_min_avail = 4 service_count = 1 } service stats { fifo_listener stats-mail { group = users mode = 01224 } } ssl = required ssl_cert = <### redacted ### ssl_key = # hidden, use -P to show it ssl_prefer_server_ciphers = yes ssl_protocols = !SSLv2 !SSLv3 !TLSv1 userdb { driver = passwd } verbose_proctitle = yes protocol imap { imap_idle_notify_interval = 10 mins imap_metadata = yes mail_max_userip_connections = 20 mail_plugins = acl stats mail_crypt imap_acl imap_stats } Regards, -- Jonathan

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[Dovecot] migration from IMAP/POP3 courier server to a remote dovecot server
by nik600 06 Apr '26

06 Apr '26

Dear all i'm planning a transparent migration from a courier server that provides both IMAP and POP3 access to users to a remote dovecot server with both IMAP and POP3 access. I have to migrate about 2500 users for 250 GB of space. I'm using dovecot 2.2.5.4 on debian6 squeeze. To make a transparent migration i have to maintain old IMAP UIDs and POP3 UIDs, so i've read http://wiki2.dovecot.org/Migration and http://wiki2.dovecot.org/Migration/Courier and http://wiki2.dovecot.org/Migration/Dsync And decided that probably the best tool to use is Dsync, as the courier-dovecot-migrate.pl<http://www.dovecot.org/tools/courier-dovecot-migrate.pl> script works only locally. I've tested the dsync following instructions reported above but after the migration of one test-account the client re-download messages. If i want to keep both IMAP UIDs and POP3 UIDs i have to sync both imapc and pop3c with two commands? doveadm -o imapc_user=foo -o pop3c_user=foo -o imapc_password=bar -o pop3c_password=bar backup -R -u user@domain imapc: doveadm -o imapc_user=foo -o pop3c_user=foo -o imapc_password=bar -o pop3c_password=bar backup -R -u user@domain pop3c: Or imapc is enough? Do you have any suggestion? Thanks -- /*************/ nik600 http://www.kumbe.it

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shared mailbox error
by Marc 19 Mar '26

19 Mar '26

I am getting this error. This file does not exist. Error: t_readlink(/xxxxxx/dbox-alt-root) failed: readlink() failed: Permission denied

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LDAP AD Quota override not working
by wt.forsaken＠gmail.com 26 Feb '26

26 Feb '26

Hi there, I'm testing the new version of Dovecot 2.4 in Debian 13 before upgrading to my customers and I'm having difficult on trying to override the user's quota. The LDAP base is from Samba4 AD and having been trying the following configuration: auth-ldap.conf.ext: ldap_uris = ldap://localhost ldap_auth_dn = cn=admin,dc=localdomain ldap_auth_dn_password = password ldap_base = ou=users, dc=localdomain passdb ldap { filter = (&(objectClass=person)(sAMAccountName=%{user})) bind = yes fields { userdb_quota_storage_size = %{ldap:telephoneNumber}B } } userdb prefetch { driver = prefetch } userdb ldap { fields { quota_storage_size = %{ldap:telephoneNumber}B } } 90-quota.conf mail_plugins { quota = yes } quota "User quota" { } quota_storage_size = 40M Since there is no quotaBytes in Samba AD, I'm testing to map the telephoneNumber parameters to override the quota, also I'm just testing a 40M to see how it works. Roundcube webmail can see the quota being overriden in its inferior bar, but when I send an email to the user which is above the quota, the journal log inform "failed to store into mailbox 'INBOX': Quota exceeded (mailbox for user is full)". I don't know how to override the quota, since in passdb section I used the "userdb_" prefix but it is not being passed to userdb when I input the "doveadm user ..." command. I don't know if I have been clear in my request, but I'd appreciate any help.

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2.4.2 breaks user iterations for LDAP
by cpfeiffer＠rev-crew.info 20 Feb '26

20 Feb '26

Hello everyone, Due to the fix for CVE-2025-30189, routines like userdb_ldap_preinit() call auth_cache_parse_key_and_fields() unconditionally, with the eventually called auth_cache_parse_key_exclude() erroring if a cache key could not be constructed. It’s also noteworthy that this call happens regardless of whether use_cache is set or not, and as of such failing to construct a cache key would cause an error even if use_cache = no was set for that database. This is however an issue for user iteration with LDAP, as documented here LDAP | Dovecot CE <https://doc.dovecot.org/2.4.2/core/config/auth/databases/ldap.html#user-ite…> . Such a userdb only has iterate_filter fields that would inherently not be containing any user variables. The call to auth_cache_parse_key_and_fields() uses a combination of ldap_base and userdb_ldap_filter anyway (so whatever is in iterate_filter isn’t considered), and for an iteration userdb as described in the documentation, the latter would be empty. Alas, I ended up getting the rather confusing error * auth: Fatal: auth-cache: dc=rev-crew,dc=info: Cache key must contain at least one variable With dc=rev-crew,dc=info being my ldap_base setting for the iteration userdb. I’m not critically dependent on the user iteration, so I’ve commented the userdb out for now, but this would need fixing. Regards, Christian Pfeiffer Hello everyone, Due to the fix for CVE-2025-30189, routines like userdb_ldap_preinit() call auth_cache_parse_key_and_fields() unconditionally, with the eventually called auth_cache_parse_key_exclude() erroring if a cache key could not be constructed. It's also noteworthy that this call happens regardless of whether use_cache is set or not, and as of such failing to construct a cache key would cause an error even if use_cache = no was set for that database. This is however an issue for user iteration with LDAP, as documented here [1]LDAP | Dovecot CE. Such a userdb only has iterate_filter fields that would inherently not be containing any user variables. The call to auth_cache_parse_key_and_fields() uses a combination of ldap_base and userdb_ldap_filter anyway (so whatever is in iterate_filter isn't considered), and for an iteration userdb as described in the documentation, the latter would be empty. Alas, I ended up getting the rather confusing error o auth: Fatal: auth-cache: dc=rev-crew,dc=info: Cache key must contain at least one variable With dc=rev-crew,dc=info being my ldap_base setting for the iteration userdb. I'm not critically dependent on the user iteration, so I've commented the userdb out for now, but this would need fixing. Regards, Christian Pfeiffer References Visible links 1. https://doc.dovecot.org/2.4.2/core/config/auth/databases/ldap.html#user-ite…

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"Synchronization corrupted index header" with mdbox: thousands of deleted e-mails reappeared in INBOX
by Ákos Szőts 17 Feb '26

17 Feb '26

Hi everyone, Suddenly, the following messages appeared in my Dovecot error log: master: Warning: Killed with signal 15 (by pid=0 uid=0 code=kill) Error: Mailbox Trash: Synchronization corrupted index header [...]/Trash/dbox-Mails/dovecot.index: uidvalidity=0, but next_uid=73 Warning: Mailbox Trash: fscking index file [...]/Trash/dbox-Mails/dovecot.index Warning: mdbox([...]/mail/storage): rebuilding indexes: Mailbox Trash index was fsck'd Warning: mdbox([...]/mail/storage): fscking index file [...]/index/inbox/storage/dovecot.map.index Error: Mailbox INBOX: [...]/INBOX/dbox-Mails/dovecot.index reset, view is now inconsistent The first message is because I restarted the container. Since then, Thunderbird shows thousands of previously deleted e-mails again in INBOX where all my messages are marked as unread. - Do you know what can cause it and how can I avoid to happen again? - Is the used mdbox storage engine that fragile? Is the fault tolerance of other engines better? I have a backup from some days ago. Is it possible to somehow revert back to it and sync the new e-mails on top of those? Version: 2.4.2. Thank you, Ákos

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2.4.2 breaks big-endian builds
by Noah Meyerhans 19 Jan '26

19 Jan '26

From the Debian s390 build log, no merging parent is NULL ............................................ : ok no merging parent sent to stats ...................................... : ok no merging parent timestamp differs .................................. : ok merge events parent NULL ............................................. : ok merge events parent sent to stats .................................... : ok skip empty parents ................................................... : ok merge events and skip empty parents .................................. : ok parent updated after send ............................................ : ok large event id ....................................................... : ok merge events global .................................................. : ok 0 / 10 tests failed test-master-service-settings.c:472: Assert(#16) failed: strstr(error, tests[i].error) != NULL test-master-service-settings: Error: Failed to parse configuration: Settings block doesn't end with NUL at offset 70 test-master-service-settings.c:472: Assert(#19) failed: strstr(error, tests[i].error) != NULL test-master-service-settings: Error: Failed to parse configuration: Settings block doesn't end with NUL at offset 84 master_service_settings_read() - binary corruption ................... : FAILED 1 / 1 tests failed make[4]: *** [Makefile:958: check-local] Error 1 make[4]: Leaving directory '/build/reproducible-path/dovecot-2.4.2+dfsg1/src/lib-master' make[3]: *** [Makefile:806: check-am] Error 2 make[3]: Leaving directory '/build/reproducible-path/dovecot-2.4.2+dfsg1/src/lib-master' make[2]: *** [Makefile:604: check-recursive] Error 1 make[2]: Leaving directory '/build/reproducible-path/dovecot-2.4.2+dfsg1/src' make[1]: *** [Makefile:739: check-recursive] Error 1 make[1]: Leaving directory '/build/reproducible-path/dovecot-2.4.2+dfsg1' The build failure was introduced with commit 41bd7a502 ("lib-settings, config: Use native CPU endianess in binary config file"). The build is successful at the previous commit, but fails at that commit. I haven't yet determined whether the failure is with the code itself or the test. Full build log is available at https://buildd.debian.org/status/fetch.php?pkg=dovecot&arch=s390x&ver=1%3A2… noah

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Panic: file imap-sieve-storage.c: line 216 (imap_sieve_add_mailbox_event): assertion failed: (ismt->src_box == NULL || ismt->src_box == src_box)
by Thomas 03 Dec '25

03 Dec '25

Hello, I'm new to dovecot and greet everyone! I come from courier-imap and updated my imap server now to dovecot-2.4.2. All user directories and files were copied 1:1. In some cases, I now receive the following message in logfiles: 2025-11-28 15:20:52.184760182 Nov 28 15:20:52 imap(Email_address_hidden)<2297539><zNQfVqhEx98l90IK>: Error: Raw backtrace: libdovecot.so.0(backtrace_append+0x39) [0x7f8eb793ab09] -> libdovecot.so.0(backtrace_get+0x22) [0x7f8eb793ac42] -> libdovecot.so.0(+0x1493fc) [0x7f8eb79493fc] -> libdovecot.so.0(+0x149491) [0x7f8eb7949491] -> libdovecot.so.0(+0x6bde2) [0x7f8eb786bde2] -> lib95_imap_sieve_plugin.so(+0x49b7) [0x7f8eb74bb9b7] -> lib95_imap_sieve_plugin.so(+0x7c8b) [0x7f8eb74bec8b] -> libdovecot-storage.so.0(index_mail_free+0xe) [0x7f8eb7cb4c9e] -> lib95_imap_sieve_plugin.so(+0x6ef5) [0x7f8eb74bdef5] -> libdovecot-storage.so.0(mail_free+0x1a) [0x7f8eb7c29bca] -> libdovecot-storage.so.0(+0xf5c52) [0x7f8eb7cc7c52] -> libdovecot-storage.so.0(mail_index_transaction_commit_full+0x8c) [0x7f8eb7ce11ec] -> libdovecot-storage.so.0(index_transaction_commit+0xf2) [0x7f8eb7cc81f2] -> libdovecot-storage.so.0(+0xcff1e) [0x7f8eb7ca1f1e] -> lib95_imap_sieve_plugin.so(+0x8576) [0x7f8eb74bf576] -> lib15_notify_plugin.so(+0x368f) [0x7f8eb7bc668f] -> lib10_quota_plugin.so(+0xd99d) [0x7f8eb74d999d] -> libdovecot-storage.so.0(mailbox_transaction_commit_get_changes+0x79) [0x7f8eb7c3bac9] -> imap(+0x1762b) [0x562bf69c462b] -> imap(command_exec+0xa4) [0x562bf69d3334] -> imap(+0x24180) [0x562bf69d1180] -> imap(+0x24214) [0x562bf69d1214] -> imap(+0x2449b) [0x562bf69d149b] -> imap(client_handle_input+0x1c5) [0x562bf69d1675] -> imap(client_input+0x73) [0x562bf69d1c33] -> libdovecot.so.0(io_loop_call_io+0x67) [0x7f8eb7960187] -> libdovecot.so.0(io_loop_handler_run_internal+0x12a) [0x7f8eb79618ba] -> libdovecot.so.0(io_loop_handler_run+0x51) [0x7f8eb7960231] -> libdovecot.so.0(io_loop_run+0x48) [0x7f8eb7960408] -> libdovecot.so.0(master_service_run+0x19e) [0x7f8eb78b011e] 2025-11-28 15:20:52.940692672 Nov 28 15:20:52 imap(Email_address_hiddene)<2297539><zNQfVqhEx98l90IK>: Fatal: master: service(imap): child 2297539 killed with signal 6 (core dumped) If I filter for "Panic" now I see: 2025-11-28 15:20:52.183676628 Nov 28 15:20:52 imap(Email_address_hidden)<2297539><zNQfVqhEx98l90IK>: Panic: file imap-sieve-storage.c: line 216 (imap_sieve_add_mailbox_event): assertion failed: (ismt->src_box == NULL || ismt->src_box == src_box) Panic repeats up to several times. In moment of crash I can find lots [# of repeats] of copies of ONE mail file in users .Trash/tmp dir. Original mail file also in e.g. INBOX/cur Please tell me wht's going on here. I checked all permission, dirs and so on. CentOS 10 s/qmail dovecot-2.4.2 dovecot-pigeonhole-2.4.2 Regards, Thomas

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