January 2026 - dovecot

"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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Configuration upgrade tool
by Aki Tuomi 15 Feb '26

15 Feb '26

Hi! To make migrating from Dovecot 2.3 to 2.4 a bit easier, we are now providing a tool that helps upgrade your existing configuration. The tool allows you to upload either a full dovecot.conf or selected ancillary configuration files from a 2.3 setup, and will attempt to convert them accordingly. You can find the tool here: https://dovecot.org/upgrader/ We do not store any of the configurations processed by the tool, nor do we track who uses it. It's offered as-is, without any warranty or guarantee. If you run into any issues, unexpected results, or have feedback about the tool, please let us know — it’s very much appreciated. Please note that the tool can make mistakes, so we strongly recommend carefully reviewing and testing the output before using it in production. There are currently no plans to release this tool as open source. Regards, Aki Tuomi Open-Xchange oy

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About mail_inbox_path and mail location
by Aki Tuomi 06 Feb '26

06 Feb '26

Hi! We've been noticing that many people are configuring mail_inbox_path. I assume that for most people this is because debian decided to include it in their default config, so that it would use /var/mail boxes for user INBOXes. If your inbox *does not* reside in some weird location, you should *not* set this setting to any value, instead you can either ensure it's commented out, or set to empty value. IN PARTICULAR, IT IS **NOT** REQUIRED SETTING. Setting it to some random weird value like '.' will just cause Problems, setting it to $MAIL_HOME/ or something else will just be either pointless or cause problems. Some most common conversions (please adjust to your environment) mail_home= /home/vmail/%u => mail_home = /home/vmail/%{user} mail_home = /home/vmail/%d/%u => mail_home = /home/vmail/%{user|domain}/%{user|username} or some variant of this. mail_location = maildir:~/ => mail_path = ~/ mail_driver = maildir mail_location = maildir:/var/srv/foo/%d/%u => mail_path = /var/srv/foo/%{user|domain}/%{user|username} mail_driver = maildir In addition you might want to convert INDEX=~/.index => mail_index_path=~/.index CONTROL=~/.control => mail_control_path=~/.control LAYOUT=fs => mailbox_list_layout=fs A minimal working config is mail_home=/home/vmail/%{user} mail_driver=maildir mail_path=~/maildir mail_uid=vmail mail_gid=vmail ## If you have settings like namespace other { location = maildir:/foo/bar } this converts into namespace other { mail_path = /foo/bar # optional, if this is matches your top level mail_driver = maildir } Hope this clears out some of the confusion. Aki

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Compiling Dovecot 2.4 on OpenBSD
by Joel Mawhorter 02 Feb '26

02 Feb '26

I'm writing to see if anyone has had success compiling Dovecot 2.4 on OpenBSD. I can't seem to find any documentation that lists prerequisites. At the moment, the 2.4.2 source tarball from the Dovecot site does not seem to compile on my OpenBSD 7.8 system and the error message is not very helpful. I'm unsure if this is just a problem of some required package not being installed. If anyone could point me to info to help move forward, I would appreciate that. Joel

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How can these MBOX files on a Dovecot-based IMAP server be converted to PST for access in Outlook?
by Rawnie Dolgato 31 Jan '26

31 Jan '26

MBOX files stored on a Dovecot-based IMAP server cannot be accessed directly in Microsoft Outlook, because Outlook does not support the MBOX file format. Outlook works with PST files, so a conversion step is mandatory. While it is technically possible to convert MBOX files to EML and then import them into Outlook, this approach is impractical for real-world scenarios. It is time-consuming, difficult to manage, and not suitable when handling bulk mailboxes or large datasets, which is typically the case with server-level backups. For this reason, an MBOX to PST conversion tool (such as BitRecover MBOX to PST Converter) is recommended. It supports bulk MBOX data, preserves folder structure and metadata, and allows selective migration based on criteria like date, sender, or subject. The process runs 100% offline, ensuring data security, and works on Windows, macOS, and Linux, making it suitable for both single and multi-mailbox migrations.

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Meaning of auth-worker disconnected message and relation to LMTP 451 errors on Ubuntu
by Kim Haverblad 31 Jan '26

31 Jan '26

Hi dovecot list, I’m troubleshooting an LMTP delivery issue with Dovecot and would appreciate clarification on the meaning and impact of the following log message, which appears repeatedly during delivery attempts: auth-worker(2961): Debug: conn unix:auth-worker (pid=2948,uid=107): Disconnected: Connection closed (fd=-1) *Environment* * OS: Ubuntu (latest LTS, fully up to date) * Dovecot: distribution package (current version for Ubuntu) * MTA: Postfix * Delivery: LMTP to Dovecot * User database: MySQL (userdb lookup succeeds) * Mail storage: Maildir * Quotas: enabled via userdb (quota_rule) *Context* * LMTP accepts the recipient and completes userdb lookup successfully. * The mailbox path, uid, gid, and quota are correctly returned. * Postfix later receives a 451 4.3.0 Temporary internal error after the DATA phase. * The above auth-worker ... Disconnected: Connection closed (fd=-1)message appears around the same time. *Questions* 1. Is this Disconnected: Connection closed (fd=-1) message expected/normal behavior for auth-worker processes once a lookup is complete? 2. Under what circumstances would this indicate a real problem versus a harmless connection teardown? 3. Could this message itself contribute to, or explain, LMTP 451 4.3.0 Temporary internal error responses? 4. Are there specific auth-worker, LMTP, or debug settings recommended to determine whether this disconnect is abnormal? So far, authentication and userdb lookups appear clean, and there are no explicit permission or quota errors logged, which makes it unclear whether this message is relevant to the delivery failure or simply informational. Any clarification on how to interpret this log entry — and how to confirm whether it is benign or problematic — would be greatly appreciated. Kind Regards, Kim Hi dovecot list, I'm troubleshooting an LMTP delivery issue with Dovecot and would appreciate clarification on the meaning and impact of the following log message, which appears repeatedly during delivery attempts: auth-worker(2961): Debug: conn unix:auth-worker (pid=2948,uid=107): Disconnected: Connection closed (fd=-1) Environment o OS: Ubuntu (latest LTS, fully up to date) o Dovecot: distribution package (current version for Ubuntu) o MTA: Postfix o Delivery: LMTP to Dovecot o User database: MySQL (userdb lookup succeeds) o Mail storage: Maildir o Quotas: enabled via userdb (quota_rule) Context o LMTP accepts the recipient and completes userdb lookup successfully. o The mailbox path, uid, gid, and quota are correctly returned. o Postfix later receives a 451 4.3.0 Temporary internal error after the DATA phase. o The above auth-worker ... Disconnected: Connection closed (fd=-1) message appears around the same time. Questions 1. Is this Disconnected: Connection closed (fd=-1) message expected/normal behavior for auth-worker processes once a lookup is complete? 2. Under what circumstances would this indicate a real problem versus a harmless connection teardown? 3. Could this message itself contribute to, or explain, LMTP 451 4.3.0 Temporary internal error responses? 4. Are there specific auth-worker, LMTP, or debug settings recommended to determine whether this disconnect is abnormal? So far, authentication and userdb lookups appear clean, and there are no explicit permission or quota errors logged, which makes it unclear whether this message is relevant to the delivery failure or simply informational. Any clarification on how to interpret this log entry -- and how to confirm whether it is benign or problematic -- would be greatly appreciated. Kind Regards, Kim

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sieve auto-creation/subscription - Thunderbird cannot re-arrange folders
by listy 31 Jan '26

31 Jan '26

Hi guys. In Thunderbird auto-subscribed folders - in my case a path with sub-folders - cannot be moved around, meaning top-bottom order. Parent folders Thunderbird shows in cursive and sub-folders (targets for sieve fules) are shown "normal" It seems impossible to re-arrange top/parent folders - but every other folder, top or not, which is not auto created & auto subscribed, Thunderbird can move around as expected. Anybody seen, anybody knows this and knows a way to "fix" it? many thanks, L.

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How can these MBOX files on a Dovecot-based IMAP server be accessed in Outlook?
by Rawnie Dolgato 31 Jan '26

31 Jan '26

MBOX files stored on a Dovecot-based IMAP server cannot be accessed directly in Microsoft Outlook, because Outlook does not support the MBOX file format. Outlook works with PST files, so a conversion step is mandatory. While it is technically possible to convert MBOX files to EML and then import them into Outlook, this approach is impractical for real-world scenarios. It is time-consuming, difficult to manage, and not suitable when handling bulk mailboxes or large datasets, which is typically the case with server-level backups. For this reason, an MBOX to PST conversion tool (such as BitRecover MBOX to PST Converter) is recommended. It supports bulk MBOX data, preserves folder structure and metadata, and allows selective migration based on criteria like date, sender, or subject. The process runs 100% offline, ensuring data security, and works on Windows, macOS, and Linux, making it suitable for both single and multi-mailbox migrations.

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Subscriptions file broken in 2.4.x against 2.3.21 (V2)
by DaLiV 31 Jan '26

31 Jan '26

Hello! /eror at update from 2.3.21 to 2.4.2 / Maildir+ currently is broken. posix - so main hierarchy separator is "/" for file "subscriptions" in versions 2.4 lost possibility to recognize v2 format also as writes v1 instead with header V2 ... so all users will lost their subscriptions and must re-subscribe depsite in folder persist file in format V2 (tab separated) ... on subscribe that appends subscriptions delimeted with "/" namespace Public { type = public prefix = Public/ mail_driver = maildir mail_path = /var/mail/Public/%{auth_user|domain}/ mail_index_private_path = pvt.idx/Public mailbox_list_layout=fs separator = / subscriptions = no list = children } seems not taking in account separators and using "." instead of "/" slighlz debugged - in subsfile_set_subscribed - that gets on subscription for processing : "name"="Public/TEST" but "separator" = "." therefore splits not and decides that is version "0" ... so - somewhere deeper or possible need additional configuration Hello! eror at update from 2.3.21 to 2.4.2 Maildir+ currently is broken. posix - so main hierarchy separator is "/" for file "subscriptions" in versions 2.4 lost possibility to recognize v2 format also as writes v1 instead with header V2 ... so all users will lost their subscriptions and must re-subscribe depsite in folder persist file in format V2 (tab separated) ... on subscribe that appends subscriptions delimeted with "/" namespace Public { type = public prefix = Public/ mail_driver = maildir mail_path = /var/mail/Public/%{auth_user|domain}/ mail_index_private_path = pvt.idx/Public mailbox_list_layout=fs separator = / subscriptions = no list = children } seems not taking in account separators and using "." instead of "/" slighlz debugged - in subsfile_set_subscribed - that gets on subscription for processing : "name"="Public/TEST" but "separator" = "." therefore splits not and decides that is version "0" ... so - somewhere deeper or possible need additional configuration

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New Member
by Jochen Becker 30 Jan '26

30 Jan '26

Hi all My name is Jochen and I have joined the list in order to get some first hand advice on my journey of migrating my SOHO mail server from 2.3 to 2.4. I set up my first server back in 2005 or so. OpenSuse and Cyrus IMAP. That went fine until all of a sudden, some 8 or 10 years ago, Suse no longer supported Cyrus directly. So I switched over to Dovecot and did not regret it. My current production server (OpenSuse Leap 16, Dovecot 2.4.2) is running fine after a recent migration. But the HW is ageing and disk usage is getting close to 80%. So I got new and larger HW. I run OpenSuse Leap 16.0 and Dovecot 2.4.2 on it. As I ran into unsurmountable problems there (could not move mail_path away from /var/mail), I decided to set up a test system under Ubuntu server 25.10. There I have got Dovecot running much better, but still, I ran into problems I could not solve for quite some time now. So here I am. I will start with questions about Dovecot on Ubuntu - my test system - because there I hope my mistakes are not as bad. Aki, thanks for taking me on board. Kind regards Jochen Mainz, Germany

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