September 2026 - dovecot

discussion about "Remove doveadm_allowed_commands setting"
by Patrick Cernko 03 Sep '26

03 Sep '26

Hi Timo, hi list, I saw this commit (https://github.com/dovecot/core/commit/2b0947986ccb72e2f5ce13f8bd4b300e94e3…) on Dovecot's github repo: > doveadm: Remove doveadm_allowed_commands setting > The setting only compared the first command name against a list, which > gave a false sense of security. Anyone who is allowed to connect to the > doveadm server can already do practically anything with the commands > that were typically allowed: most commands take a -u/-A user parameter, > and commands like sync, backup and import take parameters that access > arbitrary paths. Restricting the command name doesn't change that, so > doveadm access must be given only to trusted clients regardless. I tried to understand the detailed reasoning but I don't get it. As far as I can follow the code not only the *first command name* is checked but every command send (in the list of commands via HTTP API). From our point of view, this setting has a clear security benefit like this: > # security: we only allow specific doveadm commands via doveadm-server and some more when coming from localhost > doveadm_allowed_commands = user,who > local 127.0.0.1/8 { > doveadm_allowed_commands = user,who,"sieve list","sieve get","sieve put","sieve activate" > } It limits the allowed commands in general to who and user which are read-only. Only if the connection is comming from localhost, we additionally grant some sieve commands for our web interface to manage and test sieve rulesets (https://gitlab.mpi-klsb.mpg.de/pcernko/sieveweb) All other commands are not allowed at all, e.g. it is not possible to delete mails or use dsync via the HTTP API. This policy matches our general security policy to only grant what's needed. So, Timo, I would like to ask, why this setting has to get removed (I assume in the next release) or if it can be restored again in the main branch? Is there anyone else using this setting besides me? What do the other users think about the removal of the setting? Best regards, -- Patrick Cernko <pcernko(a)mpi-klsb.mpg.de> +49 681 9325 5815 Joint Scientific IT and Technical Service Max-Planck-Institute für Informatik & Softwaresysteme

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Dovecot and Pigeonhole v2.4.5 released
by Aki Tuomi 03 Sep '26

03 Sep '26

Hi! We are happy to publish version 2.4.5 of Dovecot and Pigeonhole. These contain CVEs, discovered by external researches. The majority of these have been discovered with help of automated code analysis tools like claude code security, which is why some of these are rather old, missed bugs. Distributions have changed - Jammy (Ubuntu 22.04) is no longer provided in repo.dovecot.org - Resolute Raccoon (Ubuntu 26.04) has been added to repo.dovecot.org No new dependencies have been added. Note that there are experimental features in 2.4, one is enabled with `--enable-experimental-mail-utf8`, and another with `--enable-experimental-imap4rev2`, and you also need to set mail_utf8_extensions=yes and imap4rev2_enabled=yes to enable them in config. https://dovecot.org/releases/2.4/dovecot-2.4.5.tar.gz https://dovecot.org/releases/2.4/dovecot-2.4.5.tar.gz.sig https://pigeonhole.dovecot.org/releases/2.4/dovecot-pigeonhole-2.4.5.tar.gz https://pigeonhole.dovecot.org/releases/2.4/dovecot-pigeonhole-2.4.5.tar.gz… Binary packages in https://repo.dovecot.org/ Docker images in https://hub.docker.com/r/dovecot/dovecot --- * CVE-2026-27852: Messages with a huge number of From/To/Cc/etc email addresses could result in excessive memory usage. * CVE-2026-33263: Submission: Login service crashes with panic once mail_max_userip_connections limit is reached. * CVE-2026-33604: The SMTP outbound dot-stuffing mechanism does not properly escape dots following a bare \r in message bodies, potentially allowing spoofed emails via malicious end-of-DATA injection. * CVE-2026-33606: Mail content stored by a user can be crafted so that it is interpreted as dsync protocol commands when an administrator later runs dsync with the stream protocol, for example during a migration. * CVE-2026-33607: IMAP LIST command could be used to cause excessive CPU usage. * CVE-2026-40014: IMAP THREAD command could have used excessive amount of CPU processing a single email with a massive number of Message-IDs in References header. * CVE-2026-40015: Invalid IMAP command sent to imap-hibernate process might crash it. * CVE-2026-40017: IMAP THREAD command could have used excessive amount of CPU processing emails with a large number of specially crafted Message-IDs in References header. The fix requires a new dovecot.index.thread file format, which is enabled only after setting dovecot_storage_version or newer. This rebuilds the index, so it will cause some extra CPU usage and extra metacache disk IO usage. It shouldn't cause (much) extra object storage IO, because all the fields should be coming from dovecot.index.cache. * CVE-2026-40203: When IMAP COMPRESS=DEFLATE was enabled, an attacker could send mails into a victim's mailbox and observe network traffic to determine whether a secret message matched a known string by comparing compressed response sizes (a CRIME-style attack). The fix resets the compression dictionary after each IMAP command, preventing information from leaking between commands. * CVE-2026-40205: If multiple OAUTH scopes were required, then this could have been only partially enforced with certain configurations. * CVE-2026-4200: XCLIENT FORWARD allows to forward key only passdb fields without the "forward_" prefix which allows connections from trusted networks to set nopasswd field which allows to skip the authentication. * CVE-2026-42391: Pre-login IMAP ID command could have used excessive amount of memory, causing the process to become killed and disconnecting all the other IMAP connections being proxied by the process. Or alternatively it could have caused excessive CPU usage, slowing down all the other IMAP connections being proxied by the process. * CVE-2026-42392: If URLAUTH is enabled, sending an invalid IMAP URLFETCH can result in an untagged NO response containing uninitialized memory, potentially leaking sensitive data. * CVE-2026-42393: Doveadm password length or API key length could still be determined via timing based attacks. * CVE-2026-42395: XCLIENT FORWARD command from login_trusted_networks could have been used to cause login processes to crash. * CVE-2026-52681: Sieve resource usage (sieve_max_cpu_time) was tracked in the active Sieve binary. Switching to a different active binary could have been used to reset (bypass) the resource usage. * CVE-2026-52687: Using IMAP COMPRESS ZSTD command can cause excessive memory usage in imap-login process, possibly making it reach vsz_limit and kill all the connections being served by the process. Fixed by disabling COMPRESS command with all other compression algorithms than the standard DEFLATE. * CVE-2026-73208: In oauth2, scope/aud checking was done with JWT tokens. Now it requires all scopes. * CVE-2026-73209: Sending IMAP COMPRESS package containing zero-length frames crashes imap or imap-login process. * auth: SIGHUP no longer flushes the passdb cache and SIGUSR2 no longer logs cache statistics. Use "doveadm auth cache flush" and the new "doveadm auth cache status" instead. * auth: The OTP authentication mechanism, the {OTP} password scheme and the passdb set-credentials support have been removed. They were unmaintained and unused. This also drops the passdb_sql_update_query setting. * config: doveconf no longer prints a flat global setting when a top-level named filter overrides the same setting. * doveadm: The doveadm protocol has been bumped to v1.4. The server uses the newer multiplex stream format with clients supporting it. Older clients keep working unchanged. * imap: Change imap_compress_on_proxy default to yes. * lib-dict-extra: Increase dict client request timeout from 30s to 65s, so it stays above the SQL/Cassandra query timeout. * lib-http: HTTP requests are now parsed strictly: obsolete line folding (obs-fold) and a bare LF line terminator are rejected. Both are request desynchronization/smuggling risks. HTTP responses are still parsed leniently. * lib-storage: A '~' in a mailbox name is now escaped only when it is at the beginning of the mailbox name, not at the beginning of every hierarchy part. Directories written by older versions are migrated automatically while listing mailboxes. * lib-var-expand: Add %{time:unix} provider and the epoch, from_epoch, date, iso8601 and escape filters. Deprecates the old time providers. * lib-var-expand: The safe filter must now be the last filter in the chain. * master: Increase the timeout after config reload before killing still running old processes from 6s to 35s, so that lib-master can stop them gracefully first. + config: Support heredoc syntax for multi-line setting values: key = <<EOD ... EOD. doveconf now outputs inline SET_FILE contents (e.g. ssl_ca) using heredoc instead of the "inline:" prefix. The "inline:" form is still accepted. + configure: Build imap-hibernate also when only kqueue notify is available. + doveadm: Add "doveadm auth cache status" command, with --reset for clearing the counters. + doveadm: dump - List all supported dump types, and print the key type also for KEM and unsupported keys. + fts-flatcurve: Add support for phrase searching. This fixes false positives where the searched words existed, but not as a phrase. + fts-flatcurve: Delete the FTS index directory also when a Maildir mailbox is deleted. + imap: Add [THROTTLED] response code to tagged replies when a plugin has throttled the command. + last-login: Add last_login_dict_fields setting for updating multiple dictionary fields at login. + lib-dcrypt: Add ML-KEM-512/768/1024 support with OpenSSL 3. + lib-dcrypt: Support AEAD with Dovecot key encryption. + lib-settings: Expand %{variables} also in strlist and boollist keys. + lib-sql: sqlite - Add sqlite_busy_timeout setting, default 1s. + login-common: Log the destination also when a proxy connection fails. + quota: Update quota-clone also when "doveadm quota recalc" is run. - Fix building on systems with a signed 32-bit time_t. - Fix building with Lua when LUA_LIBS contains linker flags such as -L. - anvil: Fix busy loop eating CPU after an admin socket connection was disconnected. - auth: Fix authentication failing after a password change when the passdb cache entry was verified by an auth worker. - auth: Fix the credentials scheme of one passdb leaking into the next one during a multi-passdb lookup. - auth: oauth2 - Fix losing userdb_* fields during OAUTHBEARER authentication. - auth: passwd-file - Fix %{passdb:...} and %{userdb:...} expansion returning garbage or crashing. - config: Fix crash in "doveconf -f" for a filter that includes a @group. - config: Fix crash when including a default @group into a filter. - config: Fix hiding secrets in doveconf output. - config: Fix startup failures with some settings containing %{variables}. - configure: Fix BUILD_IMAP_HIBERNATE detection. - doc: solr-schema-9.xml - Add the mandatory tokenizer class attribute. - doveadm: compress-connect - Fix writing server input to a non-blocking stdout. - doveadm: fs delete - Fix crash with concurrent async deletes. - doveconf: Fix bogus "Multiple settings matched" error when stdout is redirected to a file that already has content. - dsync: Fix truncating a mailbox attribute value when it is compared to the local one, e.g. truncating a Sieve script. - dsync: backup - Mailbox attributes changed or created only in the destination are now reverted or deleted. - fts-flatcurve: Ignore index directory entries that vanish during iteration. - fts: Don't run FTS optimize on forced resync. - fts: build-mail - Fix accessing Content-Type header buffer out of bounds. - imap-login, pop3-login: Tolerate SASL continuations "+" without a trailing space when proxying authentication. - imap: Don't report FETCH output stream errors as "BUG: Unknown internal error". - imap: Fix hibernation always failing on FreeBSD. - imap: Fix panic on GETMETADATA with an invalid UTF-8 mailbox pattern. - imapc: Don't send SEEEN/UNSEEN to the remote server when private indexes are used. - imapc: Fix SEARCH results pointing at wrong messages after an untagged EXPUNGE. - imapc: Fix SORT returning an empty result when search criteria were used. - imapc: Fix crash when copying a mail that was already expunged in the source mailbox. - imapc: Fix stale SEARCH/SORT results after a STORE in the same session. - imapc: Honor imapc_features=no-search also for SORT. - imapc: Properly handle search criteria that can be sent to remote server. - lib-dcrypt: Don't panic on key algorithms the backend doesn't support. - lib-dcrypt: Fix x9.62 ECDSA signatures randomly failing verification. - lib-dict-backend: cdb - Fix use-after-free of the returned key. - lib-dns-client: Fix handling of a disconnect initiated by the dns-client service. - lib-fs: Fix panic in fs_write_stream_abort(), e.g. when the disk is full during FTS indexing. - lib-index: Fix "File is already open" error when appending to the transaction log while another process is rotating it. This showed up as "NO [SERVERBUG] Internal error occurred." without any logging. - lib-ldap: Fall back to system default CA paths, needed for OpenLDAP built against GnuTLS. - lib-mail: istream-binary-converter - Fix heap use-after-free with a bodyless MIME part. - lib-mail: message-parser - Fix out of bounds read with an empty preamble, fix skipping the epilogue boundary line, and degrade to a re-parse instead of panicking with an inconsistent cached MIME tree. - lib-master: Fix kick reason when the KICK-USER-SIGNAL command arrives late, which logged "Killed with signal 15" instead of "User kicked". - lib-oauth2: jwt - Fix use-after-realloc, guard against an empty body segment and percent-encode bare "." and ".." identifiers. - lib-program-client: Fix panic upon irregular termination. - lib-settings: Fix sorting of the settings history, which caused changed defaults and renames to be ignored once a plugin registered its own history, if dovecot_config_version has been set to greater than 2.4.0. - lib-smtp: Fix assert with an empty broken localpart. - lib-smtp: xclient - Reject an invalid HELO parameter with 501. - lib-sql: pgsql - Fix binary field values for rows after the first. This mainly affected dict-sql maps with hexblob fields. - lib-ssl-iostream: Fix crash at process exit with OpenSSL 4.0. - lib-storage: Don't log an error when the client resets the connection while saving a mail. - lib-storage: Fix crash when reverting a failed mailbox deletion. - lib-storage: Fix decoded size calculation for base64 attachments, which could delete the cache record of a mail with a detached attachment. - lib-storage: Fix handling escaped mailbox names in the mailbox list index. - lib-storage: Fix rewriting non-NFC subscriptions with mUTF-7 storage names, which caused repeated rename errors. - lib-storage: Fix searching flags when the view is not up to date. This broke e.g. a pipelined UID STORE +FLAGS \Deleted followed by UID EXPUNGE. - lib-storage: Fix the mailbox vsize header not being repaired when it is corrupted, causing wrong mailbox sizes to be reported. - lib-storage: thread - Fix panic when running IMAP THREAD in multiple connections in parallel. - lib-var-expand: Reject an empty separator in the index filter, which caused an infinite loop. - lib: Fix crash and out of bounds reads when decoding IDN addresses. Reachable only with the experimental mail UTF-8 support enabled. - lib: ioloop - Fix panic and delayed timeouts when time moves forwards. - lib: ostream-multiplex - Fix stalls, busy loops and a panic when streaming data through a multiplexed connection, e.g. IMAP FETCH through a login proxy or TLS connections. - login-common: Fix connection hanging if an ostream write failed. This happened at least with HAProxy health check connections. - login-common: Fix real_remote_ip being looked up incorrectly. - login-common: Reject proxy credentials with ASCII control characters. - login-proxy: Fix "doveadm kick" for proxied connections in high-security mode, and log "Kicked by admin" as the reason. - maildir: Fix random SEARCH failures when another session concurrently expunges mails. - quota: Fix maildir quota dropping to zero after IMAP MOVE or REPLACE. - submission-login: proxy - Fix crash and unbounded memory usage with a multi-line or malformed AUTH reply from the backend. --- * CVE-2026-33605: managesieve-login: Pre-auth crash. An unauthenticated attacker can crash the ManageSieve login process by sending a small malformed command before authenticating. * CVE-2026-40019: v2.4.3 regression: managesieve-login pre-auth infinite loop. An unauthenticated attacker can send a truncated quoted argument to the ManageSieve login process, which makes it spin in an infinite loop consuming CPU. * CVE-2026-42007: sieve-editheader: An attacker that has valid credentials can use a Sieve script with the editheader extension to trigger a use-after-free in the mail editing code, and to write memory contents beyond the intended buffer in the delivered mail. * lib-sieve: sieve_max_cpu_time now defaults to 30s globally, so the limit also applies to MDA delivery. Previously the global default was unlimited and only imap_sieve used 30s. The old defaults are kept for older dovecot_config_version values. * lib-sieve: enotify - The number of notify actions performed during a single script execution is now limited to 10 by default. See the new sieve_notify_max_notifications setting. * lib-sieve: enotify - A single "mailto:" notify action is now limited to 8 recipients and 16 additional headers by default. See the new sieve_notify_mailto_max_recipients and sieve_notify_mailto_max_headers settings. * imap-filter-sieve: FILTER SIEVE SCRIPT literals larger than sieve_max_script_size are now rejected before the script is read. - lib-sieve: Fix stack overflow occurring when a script requires the same extension repeatedly. - lib-sieve: encoded-character - Fix integer overflow parsing ${unicode:...} values with 9 or more hex digits. - lib-sieve: variables - Fix integer overflow parsing numeric variable index. - lib-sieve: regex - Fix panic occurring when more than 8 group values are matched. - lib-sieve: ldap - Fix LDAP settings missing from the LDAP storage plugin. - managesieve-login: Fix capability reporting when Sieve settings use %variables.

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Minor freebsd issue on dovecot 2.4.5
by Lucas Holt 02 Sep '26

02 Sep '26

On FreeBSD and MidnightBSD, Dovecot's net_getunixcred() relies on getpeereid(), which lacks PID info, causing every imap-login connection to register with anvil as pid=-1 and collide in its per-process hash. Here's an example fix for the problem. Note this was AI generated with claude fable and I don't know what your AI policy is. --- src/lib/net.c.orig 2026-08-28 00:00:00 UTC +++ src/lib/net.c @@ -9,6 +9,9 @@ #include <fcntl.h> #include <ctype.h> #include <sys/un.h> +#ifdef __FreeBSD__ +# include <sys/ucred.h> +#endif #include <netinet/tcp.h> #if defined(HAVE_UCRED_H) # include <ucred.h> /* for getpeerucred() */ @@ -832,6 +835,26 @@ cred_r->gid = ucred.unp_egid; cred_r->pid = ucred.unp_pid; return 0; +#elif defined(LOCAL_PEERCRED) && defined(__FreeBSD__) && __FreeBSD__ >= 13 + /* FreeBSD 13+ / MidnightBSD 4+ (getpeereid() exists too, but struct + xucred also carries the peer pid, which anvil needs) */ + struct xucred ucred; + socklen_t len = sizeof(ucred); + + if (getsockopt(fd, 0, LOCAL_PEERCRED, &ucred, &len) < 0) { + i_error("getsockopt(LOCAL_PEERCRED) failed: %m"); + return -1; + } + + if (ucred.cr_version != XUCRED_VERSION) { + errno = EINVAL; + return -1; + } + + cred_r->uid = ucred.cr_uid; + cred_r->gid = ucred.cr_gid; + cred_r->pid = ucred.cr_pid; + return 0; #elif defined(HAVE_GETPEEREID) /* OSX 10.4+, FreeBSD 4.6+, OpenBSD 3.0+, NetBSD 5.0+ */ if (getpeereid(fd, &cred_r->uid, &cred_r->gid) < 0) {

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Problem with setup of 2.4
by Doug Hardie 02 Sep '26

02 Sep '26

I have a production 2.3 server on the machine named "mail". I have installed 2.4 on the server named "test". I used the configuration converter to convert the production configuration to the new configuration structure. I did add a "log_debug = category=auth" line at the end for debug info. If I use the command to the production server: master# openssl s_client -connect 10.0.1.230:imap -starttls imap -quiet Connecting to 10.0.1.230 Can't use SSL_get_servername depth=3 C=US, O=Internet Security Research Group, CN=ISRG Root X2 verify return:1 depth=2 C=US, O=ISRG, CN=Root YE verify return:1 depth=1 C=US, O=Let's Encrypt, CN=YE2 verify return:1 depth=0 CN=mail.sermon-archive.info verify return:1 . OK Pre-login capabilities listed, post-login capabilities have more. At that point I can login and view mail. However, if i use the same command on the test server: master# openssl s_client -connect 10.0.1.235:993 -starttls imap Connecting to 10.0.1.235 CONNECTED(00000003) At this point is sits there accepting no input. The log shows: Aug 31 13:56:22 test dovecot[85915]: auth: Debug: conn unix:login (uid=144) [6]: Server accepted connection (fd=21) Aug 31 13:56:22 test dovecot[85915]: auth: Debug: conn unix:login (uid=144) [6]: auth client connected (pid=86045) There appears to be an SSL issue. The same certificates are used on both servers. Both servers are running FreeBSD 15.1. dovecot.conf is: test# cat dovecot.conf # Conversion performed at 2026-08-23 05:06:46.587238 dovecot_config_version = 2.4.2 dovecot_storage_version = 2.4.0 auth_mechanisms = plain cram-md5 auth_verbose_passwords = no base_dir = /var/run/home_mail/ first_valid_gid = 0 imap_capability = SASL-IR LOGIN-REFERRALS ID ENABLE LITERAL+ STARTTLS LOGINDISABLED AUTH=CRAM-MD5 lda_mailbox_autocreate = yes login_log_format_elements = user=<%{user}> method=%{mechanism} rip=%{remote_ip} lip=%{local_ip} mpid=%{mail_pid} %{secured} %{ssl_security} session=<%{session}> port=%{local_port} mail_driver = maildir mail_gid = 2222 mail_home = /var/mail/home_mail/%{user | username} mail_log_events = delete undelete expunge copy mailbox_delete mailbox_rename mail_log_fields = uid box msgid size from mail_log_prefix = %{protocol}(%{user})[%{remote_ip}]<%{session}>: mail_path = Maildir mail_temp_scan_interval = 0 mail_uid = 2222 postmaster_address = doug(a)sermon-archive.info protocols = imap syslog_facility = local1 verbose_proctitle = yes namespace inbox { inbox = yes mailbox Drafts { autoexpunge = 5 days special_use = \Drafts } mailbox Junk { autoexpunge = 5 days special_use = \Junk } mailbox Trash { autoexpunge = 50 days special_use = \Trash } mailbox Sent { autoexpunge = 30 days special_use = \Sent } mailbox "Sent Messages" { autoexpunge = 30 days special_use = \Sent } } passdb passwd-file { auth_username_format = %{user | username} default_password_scheme = CRYPT driver = passwd-file passwd_file_path = /usr/local/etc/dovecot/users } userdb static { driver = static fields { allow_all_users = yes home = /var/mail/home_mail/%d/%n } } service imap-login { inet_listener imap { port = 143 } inet_listener imaps { port = 993 ssl = yes } inet_listener imaps2 { port = 998 ssl = yes } } service auth { unix_listener auth-userdb { group = vmail mode = 0666 user = vmail } unix_listener /var/spool/postfix/private/auth { group = postfix mode = 0660 user = postfix } } service stats { unix_listener stats-reader { group = vmail mode = 0660 user = vmail } unix_listener stats-writer { group = vmail mode = 0660 user = vmail } } ssl_server { cert_file = /www/certs/mail.pem dh_file = /usr/local/etc/dovecot/dh.pem key_file = # hidden, use -P to show it } protocol lda { mail_plugins { sieve = yes } } protocol imap { imap_metadata = yes mail_plugins { mail_log = yes notify = yes } } protocol pop3 { mail_plugins { mail_log = yes notify = yes } } #sieve_script personal { # active_path = /var/mail/home_mail/%{user | username}/.dovecot.sieve # driver = file # path = /var/mail/home_mail/%{user | username}/sieve #} mail_attribute { dict file { path = %{home}/Maildir/dovecot-attributes } } # Warnings during conversion: # - <memory>:8: dropping removed setting 'auth_stats' # - <memory>:50: mail_plugins uses $SET:mail_plugins but adds nothing # - <memory>:180: no converter for 'plugin/@1/stats_refresh' # - <memory>:181: no converter for 'plugin/@1/stats_track_cmds' # - pruned default: inbox prefix = '' log_debug = category=auth -- Doug

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Dovecot 2.4: shared mailboxes not working - maybe related to mail_path
by Markus Schönhaber 02 Sep '26

02 Sep '26

Hi, I've had a hard time trying to upgrade my dovecot 2.3 setup to v. 2.4 (debian 13, Dovecot installed from repo.dovecot.org) One thing I still haven't got to work is mailbox sharing. I have configured this (full doveconf -n output attached): mail_driver = mdbox mail_home = /var/spool/vmail/home/%{user | domain}/%{user | username} mail_path = /var/spool/vmail/mail/%{user | domain}/%{user | username} mail_plugins = quota acl namespace inbox { inbox = yes separator = / } namespace shared { mail_home = /var/spool/vmail/home/%{owner_domain}/%{owner_username} list = children prefix = shared/$domain/$username/ separator = / subscriptions = no type = shared } acl_driver = vfile mail_plugins { acl = yes } protocol imap { mail_plugins { imap_acl = yes } } acl_sharing_map { dict file { path = /var/spool/vmail/home/shared-mailboxes } } Now, given two users: 1: sharing-user(a)example.com 2: sharing-client(a)example.net User 1 wants to share his mailbox "4you" to user 2 by setting these acls: > # doveadm acl add -u sharing-user(a)example.com 4you user=sharing-client(a)example.net lookup read write-seen But the shared mailbox isn't visible for user 2 (in fact, not even the namespace is, since list = children). acl debug shows this: > # doveadm acl debug -u sharing-client(a)example.net shared/example.com/sharing-user/4you > doveadm(sharing-client(a)example.net): Error: Mailbox shared/example.com/sharing-user/4you: Mailbox '4you' in namespace shared doesn't exist in /var/spool/vmail/mail/example.net/sharing-client/mailboxes/4you/dbox-Mails So the shared mailbox is looked for in user 2's mail_path, not in user 1's, who shares it and where the mailbox actually resides. So, I tried and set mail_path = /var/spool/vmail/path/%{owner_domain}/%{owner_username} for the shared namespace. This does not only seem reasonable but also is mentioned in the second config example here: https://doc.dovecot.org/2.4.4/core/config/shared_mailboxes.html#user-shared… But that doesn't help. Instead I get: > # doveadm acl debug -u sharing-client(a)example.net shared/example.com/sharing-user/4you > doveadm(sharing-client(a)example.net): Error: Namespace shared: mail_storage settings: Failed to parse configuration: Failed to expand mail_path setting variables: Unknown variable 'owner_domain' > doveadm(sharing-client(a)example.net): Error: Namespace shared: mail_storage settings: Failed to parse configuration: Failed to expand mail_path setting variables: Unknown variable 'owner_domain' > doveadm(sharing-client(a)example.net): Error: Namespace shared: mail_storage settings: Failed to parse configuration: Failed to expand mail_path setting variables: Unknown variable 'owner_domain' > doveadm(sharing-client(a)example.net): Error: Mailbox shared/example.com/sharing-user/4you: Can't open mailbox shared/example.com/sharing-user/4you: Internal error occurred. Refer to server log for more information. [2026-08-20 14:53:40] Swapping %{owner_domain} and %{owner_username} in the config above, I get Unknown variable 'owner_username' as error. If I set mail_path = /var/spool/vmail/mail/example.com/sharing-user i. e. I hard-code the sharing user's mail_path, sharing works for this particular user. But that won't help if a second user wants to share mailboxes too. > # doveadm acl debug -u sharing-client(a)example.net shared/example.com/sharing-user/4you > doveadm(sharing-client(a)example.net): Info: Mailbox shared/example.com/sharing-user/4you: Mailbox '4you' is in namespace shared > doveadm(sharing-client(a)example.net): Info: Mailbox shared/example.com/sharing-user/4you: Mailbox path: /var/spool/vmail/mail/example.com/sharing-user/mailboxes/4you/dbox-Mails > doveadm(sharing-client(a)example.net): Info: Mailbox shared/example.com/sharing-user/4you: All message flags are shared across users in mailbox > doveadm(sharing-client(a)example.net): Info: Mailbox shared/example.com/sharing-user/4you: User sharing-client(a)example.net has rights: lookup read write-seen > doveadm(sharing-client(a)example.net): Info: Mailbox shared/example.com/sharing-user/4you: Mailbox found from dovecot-acl-list > doveadm(sharing-client(a)example.net): Info: Mailbox shared/example.com/sharing-user/4you: User sharing-user(a)example.com found from ACL shared dict > doveadm(sharing-client(a)example.net): Info: Mailbox shared/example.com/sharing-user/4you: Mailbox shared/example.com/sharing-user/4you is visible in LIST What am I doing wrong? How to do ist right? -- Regards mks

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