- dovecot - dovecot.org

Executing a sieve-extprograms pipe script as non-root
by Roland Hieber 29 Mar '26

29 Mar '26

Hi, Ultimately I'm trying to call procmail via a `pipe "procmail";` in my Sieve script on Dovecot 2.4.1. I have therefore created the respective wrapper script in /usr/lib/dovecot/sieve-pipe/procmail, but I noted that the script is apparently run as root. With some debug output in the wrapper script, I see: # `id` output uid=0(root) gid=1059(rhi) groups=1059(rhi),116(dovecot) # `pstree -s -u $$` systemd(1)---dovecot(1064)---lmtp(266577,rhi)---procmail(266706,root)---pstree(266711) This Dovecot gets mail delivered via LMTP from another server. 1059 (rhi) is my local user ID on the IMAP server both in /etc/passwd and in /etc/dovecot/users (using auth-passwdfile.conf.ext in 10-auth.conf instead of auth-system.conf.ext), since mail needs to be delivered and chown'ed correctly into Maildirs that should be user-accessible. However I don't understand how the `procmail` wrapper can be run as the root user rights when the LMTP process starting it is running as my own user?!? I'd like to prevent procmail from running as root as far as possible, so for now I've been able to work around this by wrapping the procmail call into an additional `sudo -U $USER` (after determining the user who owns the target maildir), but I'd like to understand the problem a bit further and like to know if this is really how calling sieve-extprograms is supposed to work – I'd have expected that the external scripts are also run as my unprivileged user. I'm running a fairly standard config on Debian stable (dovecot package version 1:2.4.1+dfsg1-6+deb13u2) with only minimal changes by enabling the passwdfile backend and some sieve plugins. Thanks for any insights, - Roland -- Roland Hieber, Pengutronix e.K. | rhi(a)pengutronix.de | Steuerwalder Str. 21 | https://www.pengutronix.de/ | 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |

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dovecot 2.4.x director
by Maciej Milaszewski 27 Mar '26

27 Mar '26

HI Has anyone managed to create a fork or other solution that provides director functionality? A small setup where it can be managed, for example, with Rabit/Redis, is one thing, but not a larger environment. The documentation for 2.4.x seems to have something like this: https://doc.dovecot.org/2.4.3/howto/lua_director.html "This is an unsupported method of running Dovecot. Caveat emptor. It is only intended for small-scale deployments – this is NOT designed to scale for more than a few servers."

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Dovecot Security Advisory OXDC-2026-0001
by Aki Tuomi 27 Mar '26

27 Mar '26

Hi! We're sharing our latest advisory with you and like to thank everyone who contributed in finding and solving those vulnerabilities. This advisory is also published at https://documentation.open-xchange.com/dovecot/security/advisories/html/202… --- Internal reference: DOV-7830 Type: CWE-1250 (Improper Preservation of Consistency Between Independent Representations of Shared State) Component: core Report confidence: Confirmed Solution status: Fixed by vendor Last affected revision: OX Dovecot CE core 2.4.0 First fixed revision: OX Dovecot CE core 2.4.1 Discovery date: 2025-07-24 Solution date: 2026-03-27 Disclosure date: 2026-03-27 Researcher credits: Erik <erik(a)broadlux.com> CVE: CVE-2025-30189 CVSS: 7.4 (CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N) Details: v2.4 regression: auth cache broken with several passdb / userdb. When cache is enabled, some passdb/userdb drivers incorrectly cache all users with same cache key, causing wrong cached information to be used for these users. Risk: After cached login, all subsequent logins are for same user. No publicly available exploits are known. Solution: Install fixed version or disable caching either globally or for the impacted passdb/userdb drivers. --- Internal reference: DOV-8349 Type: CWE-20 (Improper Input Validation) Component: core Report confidence: Confirmed Solution status: Fixed by vendor Last affected revision: OX Dovecot CE core 2.4.0 First fixed revision: OX Dovecot CE core 2.4.3 Discovery date: 2025-11-04 Solution date: 2026-03-27 Disclosure date: 2026-03-27 CVE: CVE-2025-59028 CVSS: 5.3 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L) Details: Invalid base64 authentication can cause DoS for other logins. When sending invalid base64 SASL data, login process is disconnected from the auth server, causing all active authentication sessions to fail. Risk: Invalid BASE64 data can be used to DoS a vulnerable server to break concurrent logins. No publicly available exploits are known. Solution: Install fixed version or disable concurrency in login processes (heavy perfomance penalty on large deployments). --- Internal reference: DOV-8508 Type: CWE-20 (Improper Input Validation) Component: core Report confidence: Confirmed Solution status: Fixed by vendor Last affected revision: OX Dovecot CE core 2.4.0 First fixed revision: OX Dovecot CE core 2.4.3 Discovery date: 2025-11-29 Solution date: 2026-03-27 Disclosure date: 2026-03-27 CVE: CVE-2025-59032 CVSS: 7.5 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H) Details: v2.4/v3.1 regression: Pigeonhole: ManageSieve panic occurs with sieve-connect as a client. ManageSieve AUTHENTICATE command crashes when using literal as SASL initial response. Risk: This can be used to crash ManageSieve service repeatedly, making it unavailable for other users. No publicly available exploits are known. Solution: Control access to ManageSieve port, or disable the service if it's not needed. Alternatively upgrade to a fixed version. --- Internal reference: DOV-8584 Type: CWE-200 (Exposure of Sensitive Information to an Unauthorized Actor) Component: core Report confidence: Confirmed Solution status: Fixed by vendor Last affected revision: OX Dovecot Pro core 2.3.0 First fixed revision: OX Dovecot CE core 2.4.3 Discovery date: 2025-12-29 Solution date: 2026-03-27 Disclosure date: 2026-03-27 Researcher credits: cavid@yeswehack CVE: CVE-2025-59031 CVSS: 4.3 (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N) Details: decode2text.sh OOXML extraction may follow symlinks and read unintended files during indexing. Dovecot has provided a script to use for attachment to text conversion. This script unsafely handles zip-style attachments. Risk: Attacker can use specially crafted OOXML documents to cause unintended files on the system to be indexed and subsequently ending up in FTS indexes. No publicly available exploits are known. Solution: Do not use the provided script, instead, use something else like FTS tika. --- Internal reference: DOV-8591 Type: CWE-22 (Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')) Component: core Report confidence: Confirmed Solution status: Fixed by vendor Last affected revision: OX Dovecot Pro core 2.3.0 First fixed revision: OX Dovecot CE core 2.4.0 Discovery date: 2026-01-07 Solution date: 2026-03-27 Disclosure date: 2026-03-27 Researcher credits: strokep@yeswehack CVE: CVE-2026-0394 CVSS: 5.3 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N) Details: auth: Path traversal in passwd-file passdb using `%d` (domain) escapes base directory and opens `/etc/passwd`Pre-auth path traversal in passwd-file passdb using `%d` (domain) escapes base directory and opens `/etc/passwd`. When dovecot has been configured to use per-domain passwd files, and they are placed one path component above /etc, or slash has been added to allowed characters, path traversal can happen if the domain component is directory partial. Risk: This allows inadvertently reading /etc/passwd (or some other path which ends with passwd). If this file contains passwords, it can be used to authenticate wrongly, or if this is userdb, it can unexpectly make system users appear valid users. No publicly available exploits are known. Solution: Upgrade to fixed version, or use different authentication scheme that does not rely on paths. Alternatively you can also ensure that the per-domain passwd files are in some other location, such as /etc/dovecot/auth/%d. --- Internal reference: DOV-8775 Type: CWE-90 (Improper Neutralization of Special Elements used in an LDAP Query ('LDAP Injection')) Component: core Report confidence: Confirmed Solution status: Fixed by vendor Last affected revision: OX Dovecot CE core 2.4.0 First fixed revision: OX Dovecot CE core 2.4.3 Discovery date: 2026-02-20 Solution date: 2026-03-27 Disclosure date: 2026-03-27 Researcher credits: cookiejack15@yeswehack CVE: CVE-2026-27860 CVSS: 3.7 (CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N) Details: v2.4/v3.1 regression: auth-ldap is not escaping usernames. If auth_username_chars is empty, it is possible to inject arbitrary LDAP filter to Dovecot's LDAP authentication. Risk: This leads to potentially bypassing restrictions and allows probing of LDAP structure. No publicly available exploits are known. Solution: Do not clear out auth_username_chars, or install fixed version. --- Internal reference: DOV-8781 Type: CWE-89 (Improper Neutralization of Special Elements used in an SQL Command ('SQL Injection')) Component: core Report confidence: Confirmed Solution status: Fixed by vendor Last affected revision: OX Dovecot CE core 2.4.0 First fixed revision: OX Dovecot CE core 2.4.3 Discovery date: 2026-02-23 Solution date: 2026-03-27 Disclosure date: 2026-03-27 Researcher credits: whisperer@yeswehack CVE: CVE-2026-24031 CVSS: 7.7 (CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:L) Details: v2.4/v3.1 regression: SQL injection allows bypassing authentication. Dovecot SQL based authentication can be bypassed when auth_username_chars is cleared by admin. Risk: This vulnerability allows bypassing authentication for any user and user enumeration. No publicly available exploits are known. Solution: Do not clear auth_username_chars. If this is not possible, install latest fixed version. --- Internal reference: DOV-8787 Type: CWE-400 (Uncontrolled Resource Consumption) Component: core Report confidence: Confirmed Solution status: Fixed by vendor Last affected revision: OX Dovecot CE core 2.4.0 First fixed revision: OX Dovecot CE core 2.4.3 Discovery date: 2026-02-24 Solution date: 2026-03-27 Disclosure date: 2026-03-27 Researcher credits: djvirus@yeswehack CVE: CVE-2026-27859 CVSS: 5.3 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L) Details: v3.0.2+ regression: Message headers MIME parameter parsing can cause excessive CPU usage. A mail message containing excessive amount of RFC 2231 MIME parameters causes LMTP to use too much CPU. Risk: A suitably formatted mail message causes mail delivery process to consume large amounts of CPU time. No publicly available exploits are known. Solution: Use MTA capabilities to limit RFC 2231 MIME parameters in mail messages, or upgrade to fixed version where the processing is limited. --- Internal reference: DOV-8816 Type: CWE-400 (Uncontrolled Resource Consumption) Component: core Report confidence: Confirmed Solution status: Fixed by vendor Last affected revision: OX Dovecot Pro core 2.3.0 First fixed revision: OX Dovecot CE core 2.4.3 Discovery date: 2026-02-27 Solution date: 2026-03-27 Disclosure date: 2026-03-27 Researcher credits: whisperer@yeswehack CVE: CVE-2026-27857 CVSS: 4.3 (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L) Details: imap-login: Excessive memory usage DoS. Sending "NOOP (((...)))" command with 4000 parenthesis open+close results in ~1MB extra memory usage. Longer commands will result in client disconnection. This 1 MB can be left allocated for longer time periods by not sending the command ending LF. So attacker could connect possibly from even a single IP and create 1000 connections to allocate 1 GB of memory, which would likely result in reaching VSZ limit and killing the process and its other proxied connections. Risk: Attacker could connect possibly from even a single IP and create 1000 connections to allocate 1 GB of memory, which would likely result in reaching VSZ limit and killing the process and its other proxied connections. No publicly available exploits are known. Solution: Install fixed version, there is no other remediation. --- Internal reference: DOV-8818 Type: CWE-400 (Uncontrolled Resource Consumption) Component: core Report confidence: Confirmed Solution status: Fixed by vendor Last affected revision: OX Dovecot Pro core 2.3.0, OX Dovecot CE core 2.4.0 First fixed revision: OX Dovecot CE core 2.4.3 Discovery date: 2026-02-28 Solution date: 2026-03-27 Disclosure date: 2026-03-27 Researcher credits: ilyar@yeswehack CVE: CVE-2026-27858 CVSS: 7.5 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H) Details: managesieve-login out-of-memory DoS. Attacker can send a specifically crafted message before authentication that causes managesieve to allocate large amount of memory. Risk: Attacker can force managesieve-login to be unavailable by repeatedly crashing the process. No publicly available exploits are known. Solution: Protect access to managesieve protocol, or install fixed version. --- Internal reference: DOV-8830 Type: CWE-287 (Improper Authentication) Component: core Report confidence: Confirmed Solution status: Fixed by vendor Last affected revision: OX Dovecot Pro core 2.3.0 First fixed revision: OX Dovecot CE core 2.4.3 Discovery date: 2026-03-04 Solution date: 2026-03-27 Disclosure date: 2026-03-27 Researcher credits: bksparajuli@yeswehack CVE: CVE-2026-27856 CVSS: 7.4 (CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N) Details: doveadm: Credentials verified without timing safety. Doveadm credentials are verified using direct comparison which is susceptible to timing oracle attack. An attacker can use this to determine the configured credentials. Risk: Figuring out the credential will lead into full access to the affected component. No publicly available exploits are known. Solution: Limit access to the doveadm http service port, install fixed version. --- Internal reference: DOV-8859 Type: CWE-294 (Authentication Bypass by Capture-replay) Component: core Report confidence: Confirmed Solution status: Fixed by vendor Last affected revision: OX Dovecot Pro core 2.3.0 First fixed revision: OX Dovecot CE core 2.4.3 Discovery date: 2026-03-09 Solution date: 2026-03-27 Disclosure date: 2026-03-27 Researcher credits: hamizanazman@yeswehack CVE: CVE-2026-27855 CVSS: 6.8 (CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N) Details: auth: OTP driver vulnerable to replay attack. Dovecot OTP authentication is vulnerable to replay attack under specific conditions. If auth cache is enabled, and username is altered in passdb, then OTP credentials can be cached so that same OTP reply is valid. Risk: An attacker able to observe an OTP exchange is able to log in as the user. No publicly available exploits are known. Solution: If authentication happens over unsecure connection, switch to SCRAM protocol. Alternatively ensure the communcations are secured, and if possible switch to OAUTH2 or SCRAM.

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Imap Sieve errors in 2.4.2
by Alberto 26 Mar '26

26 Mar '26

Hi, I have a Dovecot docker image with last version (2.4.2). I'm getting some errors, last time a few minutes ago, when dragging some emails into a folder I had just created. ... Mar 26 10:48:20 imap(alberto(a)bersol.info)<451><wHkgJepNsLRYDtBg>: Info: Mailbox INBOX.carpetanueva: Mailbox created Mar 26 10:48:24 imap(alberto(a)bersol.info)<397><x8N6YuhNMs9YDtBg>: Panic: file imap-sieve-storage.c: line 216 (imap_sieve_add_mailbox_event): assertion failed : (ismt->src_box == NULL || ismt->src_box == src_box) Mar 26 10:48:24 imap(alberto(a)bersol.info)<397><x8N6YuhNMs9YDtBg>: Error: Raw backtrace: #1 [unw_get_proc_name() failed: -10] -> #2 [unw_get_proc_name() failed: -10] -> #3 i_panic[0x7fbaed2ee8ab] -> #4 [unw_get_proc_name() failed: -1] Mar 26 10:48:24 imap(alberto(a)bersol.info)<397><x8N6YuhNMs9YDtBg>: Fatal: master: service(imap): child 397 killed with signal 6 (core dumped) This breaks Dovecot and I have to restart the container, but it doesn't fix it either. When I access again, I've receive this errors again, until I disable sieve in the imap.conf: conf.d/20-imap.conf ------------------- ... protocol imap { # Space separated list of plugins to load (default is global mail_plugins). mail_plugins { # imap_sieve = yes imap_quota = yes last_login = yes } And I have to keep "imap_sieve" disabled. Regards, Alberto

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Issues with doveadm sync
by cryintothebluesky＠gmail.com 21 Mar '26

21 Mar '26

Hello, I have two replica IMAP servers both running dovecot-2.4.2: imap1.example.com imap2.example.com I'm observing the following issues when replicating mailboxes with doveadm sync: 1. Permission errors with public and shared mailboxes For this test I delete all mailboxes on imap2.example.com and then use full sync from imap1.example.com to replicate mailboxes: # doveadm sync -f -s "" -N -l 10 -u ${user:?} ${server:?} The first time I run this command, the following error messages are logged: doveadm(XXX(a)example.com)<1363><eZzOJic5vWlTBQAAMBZ7fQ>: Error: brain S: Can't create mailbox Shared/support(a)example.com: Permission denied doveadm(XXX(a)example.com)<1334><ZV88Byg5vWk2BQAAMBZ7fQ>: Error: brain S: Can't create mailbox Public/Test: Permission denied If I wait 10 seconds and run the same sync command again, all mailboxes are replicated correctly. This only happens with public and shared mailboxes. I'm not sure of the exact cause, but it looks as if there is a race condition, where on the target server replicated ACLs are not applied immediately and this results in permission errors. Can anyone confirm the root cause? 2. Mailboxes are not always synchronised correctly For this test I'm using stateful sync. The man page states it performs a two-way sync, hence both server should end up with the same state. 1) I log into imap2.example.com and move some messages from Inbox to Drafts and Junk folders. 2) On imap1.example.com I run: doveadm sync -s "${state}" -N -l 10 -u ${user:?} ${server:?} 3) I log into imap1.example.com and sometimes observe the recently moved messages missing from Drafts and/or Junk folders. 4) The only way to resolve this issue is to either run full sync from imap1.example.com or to run another stateful sync but from imap2.example.com. Can anyone confirm if this is a bug or if stateful sync is required to be run on both IMAP servers against each other?

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Error: ldap: auth_passdb_post settings
by Ruud Baart 21 Mar '26

21 Mar '26

Dovecot 2.4.1 works fine on my Debian Trixie server. I use LDAP as backend for the users. I don't have problems. Authentication works fine. However logging show every time the following line: auth-worker(<user name@domain,::1)<109040><3v5ddOlJvrgAAAAAAAAAAAAAAAAAAAAB>: request [7]: Error: ldap: auth_passdb_post settings: Failed to parse configuration: Failed to expand passdb_fields/password setting variables: ldap: No such attribute 'userpassword' The LDAP authentication works correct. So I don't understand this message. My correct working LDAP configuration in auth-ldap.conf.ext: passdb ldap { passdb_use_worker = yes passdb_ldap_filter = (&(objectClass=PromptMailUser)(accountStatus=TRUE)(mailDeliveryaddress=%{user})) ldap_bind = yes fields { user = %{ldap:mailDeliveryaddress} password = %{ldap:userPassword} } } userdb ldap { userdb_use_worker = yes userdb_ldap_filter = (&(objectClass=PromptMailUser)(accountStatus=TRUE)(mailDeliveryaddress=%{user})) fields { home = %{ldap:mailBase} mail = %{ldap:mailMessageStore} mail_path = %{ldap:mailMessageStore} quota_storage_size = %{ldap:dovecotQuota} } }

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Panic in logs
by Kamil Jońca 21 Mar '26

21 Mar '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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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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dovecot-2.4.2: doveconf seg fault
by Eray Aslan 16 Mar '26

16 Mar '26

Running dovecot -c /dev/null -n results in: # 2.4.2 (0962ed2104): /dev/null # Pigeonhole version 2.4.2 (767418c3) Program received signal SIGSEGV, Segmentation fault. 0x00007ffff7c0f3a6 in str_to_uint () at ../lib/strnum.c:76 for a user. And the issue seems to be const unsigned char ** vs const char * mismatch: int str_to_uintmax(const char *str, uintmax_t *num_r) { const char *endp = NULL; uintmax_t n; int ret = str_parse_uintmax(str, &n, &endp); if ((ret != 0) || (*endp != '\0')) /* <--- reading via 'const char *' return -1; *num_r = n; return 0; } vs int str_parse_data_uintmax(const unsigned char *data, size_t size, uintmax_t *num_r, const unsigned char **endp_r) { const unsigned char *p = data, *pend = data + size; uintmax_t n = 0; if (p >= pend || *p < '0' || *p > '9') return -1; do { if (n >= ((uintmax_t)-1 / 10)) { if (n > (uintmax_t)-1 / 10) return -1; if ((uintmax_t)(*p - '0') > ((uintmax_t)-1 % 10)) return -1; } n = n * 10 + (*p - '0'); p++; } while (p < pend && *p >= '0' && *p <= '9'); if (endp_r != NULL) *endp_r = p; /* <--- writing via 'const unsigned char *' *num_r = n; return 0; } We don't know enough to choose which one would be preferable so that the interfaces match. It needs an informed decision as it shows up in a bunch of other places as well. More details at: https://bugs.gentoo.org/971191 Thank you -- Eray

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Issues with 2.4.1 & remote postgresql server
by Terry Braun 14 Mar '26

14 Mar '26

Hello, I'm stumped with using a remote postgresql database for authentication. I went through the process once, failed, debugged, failed again. I could successfully use psql to access the remote database from my host machine, so I do not believe the remote access is an issue. I implemented an instance using sqlite3 database and it worked just fine. ``` from auth-sql.conf.ext ``` sql_driver = pgsql pgsql 72.44.55.66 { parameters { sslmode = require user = user password = 123 dbname = db } } I'm using lmtp over sockets to deliver mail to dovecot, in order to isolate any interaction issues. With a postgresql db I get "Mailbox isn't a valid mbox file", but with changes only to auth-sql.conf.ext it fails. I can run the queries from psql and they work. I'm pretty much out of ideas of things to try. - I could not find anything to validate the syntax of the psql data. All the examples had "psql localhots {" - Because of the above, I am wondering if there may be an issue in the postgres driver somehow? - I did look at the documentation for https://www.postgresql.org/docs/current/libpq-connect.html#LIBPQ-PARAMKEYWO… but I'm unsure what is needed. Thanks for any ideas, help, hints. If someone has an example that works with 2.4.1-4 (7d8c0e5759) on debian 13 that would be great Terry

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