I recently went through the emails:task and related code with the aim of testing each of the failure codepaths and touching up the error text. I also discovered that the effects of setting DISCOURSE_SMTP_ENABLE_START_TLS=false are (mostly) nil. Setting this didn’t actually disable STARTTLS and in fact, it can coexist just fine with tls at connect time (DISCOURSE_SMTP_FORCE_TLS=true). So I’ve: removed the code that prevents both from being set: https://github.com/discourse/discourse/pull/35634/commits/0793898fad60871f942c3baa752172268d1360ec fixed the code to actually disable STARTTLS when requested: https://github.com/discourse/discourse/pull/35634/commits/e4f8b1f9efdb6f7ef9f5087be14f599ad8746230 redone the code that looks for failures and updated the text: https://github.com/discourse/discourse/pull/35634/commits/00430529459ef0b189d7576678aeeed32f1a24ee Before I merge this though, I think an admin warning in the dashboard for when DISCOURSE_SMTP_ENABLE_STARTTLS=false is being set is suitable. I imagine there’s at least one self-hoster out there who has set this but doesn’t need it and is actually relying on STARTTLS.

No, this alert shouldn’t show up on our hosting. We’ll fix it, thanks for the report as always.

[Bild] supermathie: Before I merge this though, I think an admin warning in the dashboard for when DISCOURSE_SMTP_ENABLE_STARTTLS=false is being set is suitable. @supermathie is this worth PMing every admin on every site that has this variable set? Our current problem checks system will do that, and I’m not sure it is warranted here, given that for the most part, this has a nil effect. ideally, I’d want to only show this on the dashboard without pinging admin users, not sure our current problem checks structure supports that use case.

I think it is - I find it extremely likely that given how confused many admins are around email setup, someone has this variable set when they actually depend on starttls. Nobody should have it set, probably. Is rather have a spurious warning than silently break someone’s email setup. The alternative is removing the check and neutering the variable so it does nothing at all.

It would be nice if the warning didn’t show up when the outgoing SMTP server is the localhost (ie matches the Discourse domain name) as TLS between the Docker container and the host isn’t needed as they are the same machine.

In this case you should remove the variable from the environment. Discourse will only use STARTTLS if it’s offered.

Ich hatte in der aktuellen Version den Fall - das die auskommentierte Zeile (default ist true) zusammen mit force_tls den eMail Versand unterbunden hat. Ich habe sie also einkommentiert und sie auf false gesetzt. EMail Versand funktioniert nun - aber ich habe diese Meldung im Backend… Es hängt ein wenig davon ab - auf welchem Port eurer Mailprovider läuft… beides geht nicht - und hat definitiv Auswirkungen.

I also noticed this. After updating Discourse on 28 November, I started seeing mail delivery failures with the error message Job exception: :enable_starttls and :tls are mutually exclusive. Set :tls if you're on an SMTPS connection. Set :enable_starttls if you're on an SMTP connection and using STARTTLS for secure TLS upgrade. Backtrace /var/www/discourse/vendor/bundle/ruby/3.3.0/gems/mail-2.9.0/lib/mail/network/delivery_methods/smtp.rb:159:in `build_smtp_session' /var/www/discourse/vendor/bundle/ruby/3.3.0/gems/mail-2.9.0/lib/mail/network/delivery_methods/smtp.rb:154:in `start_smtp_session' /var/www/discourse/vendor/bundle/ruby/3.3.0/gems/mail-2.9.0/lib/mail/network/delivery_methods/smtp.rb:108:in `deliver!' /var/www/discourse/vendor/bundle/ruby/3.3.0/gems/mail-2.9.0/lib/mail/message.rb:269:in `deliver!' /usr/local/lib/ruby/3.3.0/delegate.rb:87:in `method_missing' /var/www/discourse/lib/email/sender.rb:296:in `send' /var/www/discourse/app/jobs/regular/user_email.rb:80:in `send_user_email' /var/www/discourse/app/jobs/regular/user_email.rb:40:in `execute' /var/www/discourse/app/jobs/base.rb:318:in `block (2 levels) in perform' /var/www/discourse/vendor/bundle/ruby/3.3.0/gems/rails_multisite-7.0.0/lib/rails_multisite/connection_management/null_instance.rb:49:in `with_connection' /var/www/discourse/vendor/bundle/ruby/3.3.0/gems/rails_multisite-7.0.0/lib/rails_multisite/connection_management.rb:17:in `with_connection' /var/www/discourse/app/jobs/base.rb:305:in `block in perform' /var/www/discourse/app/jobs/base.rb:301:in `each' /var/www/discourse/app/jobs/base.rb:301:in `perform' /var/www/discourse/vendor/bundle/ruby/3.3.0/gems/sidekiq-7.3.9/lib/sidekiq/processor.rb:220:in `execute_job' /var/www/discourse/vendor/bundle/ruby/3.3.0/gems/sidekiq-7.3.9/lib/sidekiq/processor.rb:185:in `block (4 levels) in process' /var/www/discourse/vendor/bundle/ruby/3.3.0/gems/sidekiq-7.3.9/lib/sidekiq/middleware/chain.rb:180:in `traverse' /var/www/discourse/vendor/bundle/ruby/3.3.0/gems/sidekiq-7.3.9/lib/sidekiq/middleware/chain.rb:183:in `block in traverse' /var/www/discourse/lib/sidekiq/suppress_user_email_errors.rb:6:in `call' /var/www/discourse/vendor/bundle/ruby/3.3.0/gems/sidekiq-7.3.9/lib/sidekiq/middleware/chain.rb:182:in `traverse' /var/www/discourse/vendor/bundle/ruby/3.3.0/gems/sidekiq-7.3.9/lib/sidekiq/middleware/chain.rb:183:in `block in traverse' /var/www/discourse/lib/sidekiq/discourse_event.rb:6:in `call' /var/www/discourse/vendor/bundle/ruby/3.3.0/gems/sidekiq-7.3.9/lib/sidekiq/middleware/chain.rb:182:in `traverse' /var/www/discourse/vendor/bundle/ruby/3.3.0/gems/sidekiq-7.3.9/lib/sidekiq/middleware/chain.rb:183:in `block in traverse' /var/www/discourse/lib/sidekiq/pausable.rb:131:in `call' /var/www/discourse/vendor/bundle/ruby/3.3.0/gems/sidekiq-7.3.9/lib/sidekiq/middleware/chain.rb:182:in `traverse' /var/www/discourse/vendor/bundle/ruby/3.3.0/gems/sidekiq-7.3.9/lib/sidekiq/middleware/chain.rb:183:in `block in traverse' /var/www/discourse/vendor/bundle/ruby/3.3.0/gems/sidekiq-7.3.9/lib/sidekiq/job/interrupt_handler.rb:9:in `call' /var/www/discourse/vendor/bundle/ruby/3.3.0/gems/sidekiq-7.3.9/lib/sidekiq/middleware/chain.rb:182:in `traverse' /var/www/discourse/vendor/bundle/ruby/3.3.0/gems/sidekiq-7.3.9/lib/sidekiq/middleware/chain.rb:183:in `block in traverse' /var/www/discourse/vendor/bundle/ruby/3.3.0/gems/sidekiq-7.3.9/lib/sidekiq/metrics/tracking.rb:26:in `track' /var/www/discourse/vendor/bundle/ruby/3.3.0/gems/sidekiq-7.3.9/lib/sidekiq/metrics/tracking.rb:134:in `call' /var/www/discourse/vendor/bundle/ruby/3.3.0/gems/sidekiq-7.3.9/lib/sidekiq/middleware/chain.rb:182:in `traverse' /var/www/discourse/vendor/bundle/ruby/3.3.0/gems/sidekiq-7.3.9/lib/sidekiq/middleware/chain.rb:173:in `invoke' /var/www/discourse/vendor/bundle/ruby/3.3.0/gems/sidekiq-7.3.9/lib/sidekiq/processor.rb:184:in `block (3 levels) in process' /var/www/discourse/vendor/bundle/ruby/3.3.0/gems/sidekiq-7.3.9/lib/sidekiq/processor.rb:145:in `block (6 levels) in dispatch' /var/www/discourse/vendor/bundle/ruby/3.3.0/gems/sidekiq-7.3.9/lib/sidekiq/job_retry.rb:118:in `local' /var/www/discourse/vendor/bundle/ruby/3.3.0/gems/sidekiq-7.3.9/lib/sidekiq/processor.rb:144:in `block (5 levels) in dispatch' /var/www/discourse/vendor/bundle/ruby/3.3.0/gems/sidekiq-7.3.9/lib/sidekiq/config.rb:39:in `block in ' /var/www/discourse/vendor/bundle/ruby/3.3.0/gems/sidekiq-7.3.9/lib/sidekiq/processor.rb:139:in `block (4 levels) in dispatch' /var/www/discourse/vendor/bundle/ruby/3.3.0/gems/sidekiq-7.3.9/lib/sidekiq/processor.rb:281:in `stats' /var/www/discourse/vendor/bundle/ruby/3.3.0/gems/sidekiq-7.3.9/lib/sidekiq/processor.rb:134:in `block (3 levels) in dispatch' /var/www/discourse/vendor/bundle/ruby/3.3.0/gems/sidekiq-7.3.9/lib/sidekiq/job_logger.rb:15:in `call' /var/www/discourse/vendor/bundle/ruby/3.3.0/gems/sidekiq-7.3.9/lib/sidekiq/processor.rb:133:in `block (2 levels) in dispatch' /var/www/discourse/vendor/bundle/ruby/3.3.0/gems/sidekiq-7.3.9/lib/sidekiq/job_retry.rb:85:in `global' /var/www/discourse/vendor/bundle/ruby/3.3.0/gems/sidekiq-7.3.9/lib/sidekiq/processor.rb:132:in `block in dispatch' /var/www/discourse/vendor/bundle/ruby/3.3.0/gems/sidekiq-7.3.9/lib/sidekiq/job_logger.rb:40:in `prepare' /var/www/discourse/vendor/bundle/ruby/3.3.0/gems/sidekiq-7.3.9/lib/sidekiq/processor.rb:131:in `dispatch' /var/www/discourse/vendor/bundle/ruby/3.3.0/gems/sidekiq-7.3.9/lib/sidekiq/processor.rb:183:in `block (2 levels) in process' /var/www/discourse/vendor/bundle/ruby/3.3.0/gems/sidekiq-7.3.9/lib/sidekiq/processor.rb:182:in `handle_interrupt' /var/www/discourse/vendor/bundle/ruby/3.3.0/gems/sidekiq-7.3.9/lib/sidekiq/processor.rb:182:in `block in process' /var/www/discourse/vendor/bundle/ruby/3.3.0/gems/sidekiq-7.3.9/lib/sidekiq/processor.rb:181:in `handle_interrupt' /var/www/discourse/vendor/bundle/ruby/3.3.0/gems/sidekiq-7.3.9/lib/sidekiq/processor.rb:181:in `process' /var/www/discourse/vendor/bundle/ruby/3.3.0/gems/sidekiq-7.3.9/lib/sidekiq/processor.rb:86:in `process_one' /var/www/discourse/vendor/bundle/ruby/3.3.0/gems/sidekiq-7.3.9/lib/sidekiq/processor.rb:76:in `run' /var/www/discourse/vendor/bundle/ruby/3.3.0/gems/sidekiq-7.3.9/lib/sidekiq/component.rb:10:in `watchdog' /var/www/discourse/vendor/bundle/ruby/3.3.0/gems/sidekiq-7.3.9/lib/sidekiq/component.rb:19:in `block in safe_thread' Just like Johann Christoph, I previously had DISCOURSE_SMTP_ENABLE_START_TLS commented out and DISCOURSE_SMTP_FORCE_TLS set to true for implicit TLS and it worked like a charm. But now I have to explicitly set DISCOURSE_SMTP_ENABLE_START_TLS to false for email delivery to work, which of course triggers the aforementioned message in the admin dashboard.

[Bild] josy38: together with force_tls prevented email sending It will be force_tls preventing email sending - this enforces TLS at connection time and is probably only suitable for port 465. [Bild] J5lx: But now I have to explicitly set DISCOURSE_SMTP_ENABLE_START_TLS to false for email delivery to work A unicorn! What SMTP parameters are you using (minus username/password)?

Port 465 with ENABLE_START_TLS=false, FORCE_TLS=true and OPEN_TIMEOUT=10. That last one is due to strange timeout errors that I started seeing after a system update around three years ago, but I’ll eat my hat if that’s related to the issue described above. I had a look at the commit history in the meantime and noticed the mail gem was updated to version 2.9.0 just three days before the update that introduced the issue on my end (#36254). There’s an entry in the release notes of that which says “SMTP: refactor and accept starttls :always and :auto by @eval in #1536”. I don’t know much about Ruby, but this change in the referenced PR looks kind of suspicious to me: [image] Given that DISCOURSE_SMTP_ENABLE_START_TLS is documented to be true by default (i.e. if commented out), is it possible that this is the root of the issue?

[Bild] J5lx: DISCOURSE_SMTP_FORCE_TLS Wie ich schrieb - habe ich force_TLS gesetzt: `DISCOURSE_SMTP_FORCE_TLS = true` und ENABLE_START_TLS explizit auf false… dann funktioniert der Mailversand - sofern der Mailserver auf 465 läuft. Bei Mailservern die auf 567 laufen - muss es genau anders herum sein. Seither habe ich zwar einen Hinweis auf dem Dashboard im Backend… aber der Mailversand arbeitet ohne Probleme.

Überarbeitung der E-Mails: Test-Rake-Task-Ausgabe

Entwickler

supermathie (Michael Brown) 16. Dezember 2025 um 14:52 18

Dies ist nun zusammengeführt, man muss STARTTLS nicht mehr explizit deaktivieren, Discourse kümmert sich automatisch darum, wenn TLS aktiviert ist.

Thema		Antworten	Aufrufe
SSL/TLS for port 465 (Net::ReadTimeout) - undocumented solution Self-hosting email	2	838	11. November 2025
SMTP error: Must issue a STARTTLS command first Self-hosting	9	3635	23. November 2021
Email not working (SSL_connect returned=1) Self-hosting	15	2900	15. Juni 2022
Can't send email with certificate issue Self-hosting	2	1671	2. April 2019
Discourse with other websites, SMTP issue: End of file reached Self-hosting	7	2571	22. September 2020

Überarbeitung der E-Mails: Test-Rake-Task-Ausgabe

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