Generic Cannot connect to SMTP server error, no outgoing smtp connections
Dear Users,
I'm debugging since several days a mailman3 installation and can not get mailman to deliver mails to list members.
Mailman logs Cannot connect to SMTP server, however the server is listening, but i see no connection attempts.
In queue/out, i see changing files all the time:
drwxrwx--- 2 mailman nogroup 4.0K Jun 4 13:04 . drwxr-xr-x 15 mailman nogroup 4.0K Jun 4 08:22 .. -rw-rw---- 1 mailman nogroup 6.1K Jun 4 12:22 1780575734.9281623+0ad5f564c9fc5f27750a09b948f3480d9047cbaa.pck.tmp -rw-rw---- 1 mailman nogroup 6.1K Jun 4 13:04 1780578250.2070453+752ca17af5c64af7aab5f0fc61ac2ea28b091825.bak 038b90c74d8d:/opt/mailman/var/queue/out# ls -alh total 24K drwxrwx--- 2 mailman nogroup 4.0K Jun 4 13:04 . drwxr-xr-x 15 mailman nogroup 4.0K Jun 4 08:22 .. -rw-rw---- 1 mailman nogroup 6.1K Jun 4 12:22 1780575734.9281623+0ad5f564c9fc5f27750a09b948f3480d9047cbaa.pck.tmp -rw-rw---- 1 mailman nogroup 6.1K Jun 4 13:04 1780578250.7552953+6350a013583657c317c0a64b9cf2039dca645974.bak 038b90c74d8d:/opt/mailman/var/queue/out#
SMTP/DEBUG-Log is flooded with over and over same attempts:
==> /opt/mailman/core/var/logs/smtp.log <== Jun 04 13:04:46 2026 (26) Using agent: <mailman.mta.deliver.Deliver object at 0x79ed98555310> Jun 04 13:04:46 2026 (26) IndividualDelivery to: cubewerk@gmail.com
==> /opt/mailman/core/var/logs/debug.log <== Jun 04 13:04:46 2026 (31) [VirginRunner] starting oneloop Jun 04 13:04:46 2026 (31) [VirginRunner] ending oneloop: 0 Jun 04 13:04:46 2026 (26) [OutgoingRunner] finishing filebase: 1780578286.711373+091038a49a00758fdd2ba5265714e2fa31ea4843 Jun 04 13:04:46 2026 (26) [OutgoingRunner] doing periodic Jun 04 13:04:46 2026 (26) [OutgoingRunner] committing transaction Jun 04 13:04:46 2026 (26) [OutgoingRunner] checking short circuit Jun 04 13:04:46 2026 (26) [OutgoingRunner] ending oneloop: 1 Jun 04 13:04:46 2026 (26) [OutgoingRunner] starting oneloop Jun 04 13:04:46 2026 (26) [OutgoingRunner] processing filebase: 1780578286.7329357+2ec378350ee99307adc287fc8727fb9120a385d3 Jun 04 13:04:46 2026 (26) [OutgoingRunner] processing onefile Jun 04 13:04:46 2026 (26) [outgoing] <function deliver at 0x79ed98b85d00>: <gxZS.-LyKCSHn9UWsyVepCakA9g@flTQyy2_BUC0KFtMliiieCkabFXP1SdNnP1xIyNQp-k.xz>
==> /opt/mailman/core/var/logs/smtp.log <== Jun 04 13:04:46 2026 (26) Using agent: <mailman.mta.deliver.Deliver object at 0x79ed98a43bf0> Jun 04 13:04:46 2026 (26) IndividualDelivery to: cubewerk@gmail.com
If i restart the docker-core container, i see a single time the error "Cannot connect to SMTP server 172.17.0.1 on port 587".
my config:
[runner.retry] sleep_time: 10s
[webservice] hostname: 172.18.0.2 port: 8001 admin_user: restadmin admin_pass: restpass configuration: /etc/gunicorn.cfg
[mta] incoming: mailman.mta.postfix.LMTP outgoing: mailman.mta.deliver.deliver lmtp_host: 172.18.0.2 lmtp_port: 8024 smtp_host: 172.17.0.1 smtp_port: 587 smtp_user: smtp_pass: smtp_secure_mode: starttls smtp_verify_hostname: false smtp_verify_cert: false configuration: /etc/postfix-mailman.cfg
[logging.smtp] level: debug
[logging.error] level: debug
[logging.debug] level: debug
[archiver.mail_archive] enable: no configuration: /opt/mailman/mail_archive_dummy.cfg [archiver.hyperkitty] class: mailman_hyperkitty.Archiver enable: yes configuration: /etc/mailman-hyperkitty.cfg
Any helps is greatly appreciated.
thank you.
Stefan
Does outbound email work for other applications?
Does something like
mail -s 'Test Email' cubewerk@gmail.com < /opt/mailman/core/var/logs/smtp.log
work?
On Thu, Jun 4, 2026 at 9:10 AM Stefan Bauer via Mailman-users < mailman-users@mailman3.org> wrote:
Dear Users,
I'm debugging since several days a mailman3 installation and can not get mailman to deliver mails to list members.
Mailman logs Cannot connect to SMTP server, however the server is listening, but i see no connection attempts.
In queue/out, i see changing files all the time:
drwxrwx--- 2 mailman nogroup 4.0K Jun 4 13:04 . drwxr-xr-x 15 mailman nogroup 4.0K Jun 4 08:22 .. -rw-rw---- 1 mailman nogroup 6.1K Jun 4 12:22 1780575734.9281623+0ad5f564c9fc5f27750a09b948f3480d9047cbaa.pck.tmp -rw-rw---- 1 mailman nogroup 6.1K Jun 4 13:04 1780578250.2070453+752ca17af5c64af7aab5f0fc61ac2ea28b091825.bak 038b90c74d8d:/opt/mailman/var/queue/out# ls -alh total 24K drwxrwx--- 2 mailman nogroup 4.0K Jun 4 13:04 . drwxr-xr-x 15 mailman nogroup 4.0K Jun 4 08:22 .. -rw-rw---- 1 mailman nogroup 6.1K Jun 4 12:22 1780575734.9281623+0ad5f564c9fc5f27750a09b948f3480d9047cbaa.pck.tmp -rw-rw---- 1 mailman nogroup 6.1K Jun 4 13:04 1780578250.7552953+6350a013583657c317c0a64b9cf2039dca645974.bak 038b90c74d8d:/opt/mailman/var/queue/out#
SMTP/DEBUG-Log is flooded with over and over same attempts:
==> /opt/mailman/core/var/logs/smtp.log <== Jun 04 13:04:46 2026 (26) Using agent: <mailman.mta.deliver.Deliver object at 0x79ed98555310> Jun 04 13:04:46 2026 (26) IndividualDelivery to: cubewerk@gmail.com
==> /opt/mailman/core/var/logs/debug.log <== Jun 04 13:04:46 2026 (31) [VirginRunner] starting oneloop Jun 04 13:04:46 2026 (31) [VirginRunner] ending oneloop: 0 Jun 04 13:04:46 2026 (26) [OutgoingRunner] finishing filebase: 1780578286.711373+091038a49a00758fdd2ba5265714e2fa31ea4843 Jun 04 13:04:46 2026 (26) [OutgoingRunner] doing periodic Jun 04 13:04:46 2026 (26) [OutgoingRunner] committing transaction Jun 04 13:04:46 2026 (26) [OutgoingRunner] checking short circuit Jun 04 13:04:46 2026 (26) [OutgoingRunner] ending oneloop: 1 Jun 04 13:04:46 2026 (26) [OutgoingRunner] starting oneloop Jun 04 13:04:46 2026 (26) [OutgoingRunner] processing filebase: 1780578286.7329357+2ec378350ee99307adc287fc8727fb9120a385d3 Jun 04 13:04:46 2026 (26) [OutgoingRunner] processing onefile Jun 04 13:04:46 2026 (26) [outgoing] <function deliver at 0x79ed98b85d00>: <gxZS.-LyKCSHn9UWsyVepCakA9g@flTQyy2_BUC0KFtMliiieCkabFXP1SdNnP1xIyNQp-k.xz
==> /opt/mailman/core/var/logs/smtp.log <== Jun 04 13:04:46 2026 (26) Using agent: <mailman.mta.deliver.Deliver object at 0x79ed98a43bf0> Jun 04 13:04:46 2026 (26) IndividualDelivery to: cubewerk@gmail.com
If i restart the docker-core container, i see a single time the error "Cannot connect to SMTP server 172.17.0.1 on port 587".
my config:
[runner.retry] sleep_time: 10s
[webservice] hostname: 172.18.0.2 port: 8001 admin_user: restadmin admin_pass: restpass configuration: /etc/gunicorn.cfg
[mta] incoming: mailman.mta.postfix.LMTP outgoing: mailman.mta.deliver.deliver lmtp_host: 172.18.0.2 lmtp_port: 8024 smtp_host: 172.17.0.1 smtp_port: 587 smtp_user: smtp_pass: smtp_secure_mode: starttls smtp_verify_hostname: false smtp_verify_cert: false configuration: /etc/postfix-mailman.cfg
[logging.smtp] level: debug
[logging.error] level: debug
[logging.debug] level: debug
[archiver.mail_archive] enable: no configuration: /opt/mailman/mail_archive_dummy.cfg [archiver.hyperkitty] class: mailman_hyperkitty.Archiver enable: yes configuration: /etc/mailman-hyperkitty.cfg
Any helps is greatly appreciated.
thank you.
Stefan
Mailman-users mailing list -- mailman-users@mailman3.org To unsubscribe send an email to mailman-users-leave@mailman3.org https://lists.mailman3.org/mailman3/lists/mailman-users.mailman3.org/ Archived at: https://lists.mailman3.org/archives/list/mailman-users@mailman3.org/message/...
This message sent to swd@pobox.com
Yes it does.
Am Do., 4. Juni 2026 um 15:33 Uhr schrieb Stephen Daniel <swd@pobox.com>:
Does outbound email work for other applications?
Does something like
mail -s 'Test Email' cubewerk@gmail.com < /opt/mailman/core/var/logs/smtp.log
work?
On Thu, Jun 4, 2026 at 9:10 AM Stefan Bauer via Mailman-users < mailman-users@mailman3.org> wrote:
Dear Users,
I'm debugging since several days a mailman3 installation and can not get mailman to deliver mails to list members.
Mailman logs Cannot connect to SMTP server, however the server is listening, but i see no connection attempts.
In queue/out, i see changing files all the time:
drwxrwx--- 2 mailman nogroup 4.0K Jun 4 13:04 . drwxr-xr-x 15 mailman nogroup 4.0K Jun 4 08:22 .. -rw-rw---- 1 mailman nogroup 6.1K Jun 4 12:22 1780575734.9281623+0ad5f564c9fc5f27750a09b948f3480d9047cbaa.pck.tmp -rw-rw---- 1 mailman nogroup 6.1K Jun 4 13:04 1780578250.2070453+752ca17af5c64af7aab5f0fc61ac2ea28b091825.bak 038b90c74d8d:/opt/mailman/var/queue/out# ls -alh total 24K drwxrwx--- 2 mailman nogroup 4.0K Jun 4 13:04 . drwxr-xr-x 15 mailman nogroup 4.0K Jun 4 08:22 .. -rw-rw---- 1 mailman nogroup 6.1K Jun 4 12:22 1780575734.9281623+0ad5f564c9fc5f27750a09b948f3480d9047cbaa.pck.tmp -rw-rw---- 1 mailman nogroup 6.1K Jun 4 13:04 1780578250.7552953+6350a013583657c317c0a64b9cf2039dca645974.bak 038b90c74d8d:/opt/mailman/var/queue/out#
SMTP/DEBUG-Log is flooded with over and over same attempts:
==> /opt/mailman/core/var/logs/smtp.log <== Jun 04 13:04:46 2026 (26) Using agent: <mailman.mta.deliver.Deliver object at 0x79ed98555310> Jun 04 13:04:46 2026 (26) IndividualDelivery to: cubewerk@gmail.com
==> /opt/mailman/core/var/logs/debug.log <== Jun 04 13:04:46 2026 (31) [VirginRunner] starting oneloop Jun 04 13:04:46 2026 (31) [VirginRunner] ending oneloop: 0 Jun 04 13:04:46 2026 (26) [OutgoingRunner] finishing filebase: 1780578286.711373+091038a49a00758fdd2ba5265714e2fa31ea4843 Jun 04 13:04:46 2026 (26) [OutgoingRunner] doing periodic Jun 04 13:04:46 2026 (26) [OutgoingRunner] committing transaction Jun 04 13:04:46 2026 (26) [OutgoingRunner] checking short circuit Jun 04 13:04:46 2026 (26) [OutgoingRunner] ending oneloop: 1 Jun 04 13:04:46 2026 (26) [OutgoingRunner] starting oneloop Jun 04 13:04:46 2026 (26) [OutgoingRunner] processing filebase: 1780578286.7329357+2ec378350ee99307adc287fc8727fb9120a385d3 Jun 04 13:04:46 2026 (26) [OutgoingRunner] processing onefile Jun 04 13:04:46 2026 (26) [outgoing] <function deliver at 0x79ed98b85d00>:
<gxZS.-LyKCSHn9UWsyVepCakA9g@flTQyy2_BUC0KFtMliiieCkabFXP1SdNnP1xIyNQp-k.xz
==> /opt/mailman/core/var/logs/smtp.log <== Jun 04 13:04:46 2026 (26) Using agent: <mailman.mta.deliver.Deliver object at 0x79ed98a43bf0> Jun 04 13:04:46 2026 (26) IndividualDelivery to: cubewerk@gmail.com
If i restart the docker-core container, i see a single time the error "Cannot connect to SMTP server 172.17.0.1 on port 587".
my config:
[runner.retry] sleep_time: 10s
[webservice] hostname: 172.18.0.2 port: 8001 admin_user: restadmin admin_pass: restpass configuration: /etc/gunicorn.cfg
[mta] incoming: mailman.mta.postfix.LMTP outgoing: mailman.mta.deliver.deliver lmtp_host: 172.18.0.2 lmtp_port: 8024 smtp_host: 172.17.0.1 smtp_port: 587 smtp_user: smtp_pass: smtp_secure_mode: starttls smtp_verify_hostname: false smtp_verify_cert: false configuration: /etc/postfix-mailman.cfg
[logging.smtp] level: debug
[logging.error] level: debug
[logging.debug] level: debug
[archiver.mail_archive] enable: no configuration: /opt/mailman/mail_archive_dummy.cfg [archiver.hyperkitty] class: mailman_hyperkitty.Archiver enable: yes configuration: /etc/mailman-hyperkitty.cfg
Any helps is greatly appreciated.
thank you.
Stefan
Mailman-users mailing list -- mailman-users@mailman3.org To unsubscribe send an email to mailman-users-leave@mailman3.org https://lists.mailman3.org/mailman3/lists/mailman-users.mailman3.org/ Archived at: https://lists.mailman3.org/archives/list/mailman-users@mailman3.org/message/...
This message sent to swd@pobox.com
Stefan Bauer via Mailman-users wrote:
Mailman logs Cannot connect to SMTP server, however the server is listening, but i see no connection attempts. [...] If i restart the docker-core container, i see a single time the error "Cannot connect to SMTP server 172.17.0.1 on port 587".
Is it possibly to connect e.g. via telnet (from the host/IP mailman is running on, as the user mailman is running as) to the SMTP server? That looks more like a connection problem from A to B than a mailman problem.
-thh
I found the problem. Thanks for your help:
As mailman3 via docker, consists of 2 independent containers (mailman-core & web) the templates, the runner used a wrong url when looking for templates. after adjusting my templates via SQL, all is fine now:
# sqlite3 /opt/mailman/core/var/data/mailman.db "SELECT * FROM template;" 1|list:user:notice:probe|cubewerk.de| http://localhost:8000/postorius/api/templates/domain/cubewerk.de/list:user:notice:probe|| 3|list:member:regular:footer|cubewerk.de| http://localhost:8000/postorius/api/templates/domain/cubewerk.de/list:member:regular:footer|| 4|list:member:regular:footer|lists.cubewerk.de| http://localhost:8000/postorius/api/templates/domain/lists.cubewerk.de/list:member:regular:footer||
sqlite3 /opt/mailman/core/var/data/mailman.db "UPDATE template SET uri = REPLACE(uri, 'localhost:8000', '172.18.0.3:8000');"
# sqlite3 /opt/mailman/core/var/data/mailman.db "SELECT * FROM template;" 1|list:user:notice:probe|cubewerk.de| http://172.18.0.3:8000/postorius/api/templates/domain/cubewerk.de/list:user:notice:probe|| 3|list:member:regular:footer|cubewerk.de| http://172.18.0.3:8000/postorius/api/templates/domain/cubewerk.de/list:member:regular:footer|| 4|list:member:regular:footer|lists.cubewerk.de| http://172.18.0.3:8000/postorius/api/templates/domain/lists.cubewerk.de/list:member:regular:footer||
Am Do., 4. Juni 2026 um 16:48 Uhr schrieb Thomas Hochstein <thh@thh.name>:
Stefan Bauer via Mailman-users wrote:
Mailman logs Cannot connect to SMTP server, however the server is listening, but i see no connection attempts. [...] If i restart the docker-core container, i see a single time the error "Cannot connect to SMTP server 172.17.0.1 on port 587".
Is it possibly to connect e.g. via telnet (from the host/IP mailman is running on, as the user mailman is running as) to the SMTP server? That looks more like a connection problem from A to B than a mailman problem.
-thh
Mailman-users mailing list -- mailman-users@mailman3.org To unsubscribe send an email to mailman-users-leave@mailman3.org https://lists.mailman3.org/mailman3/lists/mailman-users.mailman3.org/ Archived at: https://lists.mailman3.org/archives/list/mailman-users@mailman3.org/message/...
This message sent to cubewerk@gmail.com
On 6/4/26 6:09 AM, Stefan Bauer via Mailman-users wrote:
Dear Users,
I'm debugging since several days a mailman3 installation and can not get mailman to deliver mails to list members.
Mailman logs Cannot connect to SMTP server, however the server is listening, but i see no connection attempts.
This issue with unobtainable templates and a misleading log message is <https://gitlab.com/mailman/mailman/-/issues/514> and the logging is improved for the next release by <https://gitlab.com/mailman/mailman/-/merge_requests/1362>.
-- Mark Sapiro <mark@msapiro.net> The highway is for gamblers, San Francisco Bay Area, California better use your sense - B. Dylan
participants (4)
-
Mark Sapiro -
Stefan Bauer -
Stephen Daniel -
Thomas Hochstein