I can’t get SMTP setup working with Discourse and GMail’s SMTP I enabled SMTP Relay in Google’s settings, allowed sending from my domain (no IP whitelisting), using SMTP auth + encryption. Discourse is hosted on forum.example.com DISCOURSE_SMTP_ADDRESS: smtp-relay.gmail.com DISCOURSE_SMTP_PORT: 587 DISCOURSE_SMTP_USER_NAME: noreply@example.com DISCOURSE_SMTP_PASSWORD: password DISCOURSE_SMTP_AUTHENTICATION: login DISCOURSE_SMTP_DOMAIN: mydomain.io DISCOURSE_NOTIFICATION_EMAIL: noreply@example.com DISCOURSE_SMTP_ENABLE_START_TLS: true I had generic error Job exception: end of file reached, when I added NOTIFICATION_EMAIL and SMTP_DOMAIN envs, now I’m seeing 503 5.5.1 bad sequence of commands x20sm63393lfr.126 - gsmtp when running doctor and trying to send email to myself. Changed DISCOURSE_SMTP_DOMAIN to match forum.mydomain.io and still have the same error. How I’m supposed to debug this further other than changing env, rebuilding and hoping that it works? Thanks in advance.

Instead of rebuilding you can ./launcher destroy app ./launcher start app There are some topics about getting the Google whatever working. It’s possible, but not easy. And it probably changes every month. :wink:

While I belief that @kvsf 's error is either already fixed or some fundamental things within your configuration have been changed I would like to continue this thread by posting my own configuration, my further approach and my seek for help within the same problem-domain. Basic Configuration Google Workspace Business Starter Configure Gmail-Routing > SMTP-Relay with i) only registered users from within domain, ii) IP-whitelisting with my forum-hosting server-IP and enforcing SMTP-Authentification, iii) enforcing TLS discourse docker installation according to discourse-documentation app.yml config according to expose: - "80:80" # http - "443:443" # https env: DISCOURSE_HOSTNAME: "forum.mydomain.com" DISCOURSE_DEVELOPER_EMAILS: 'dev@mydomain.com' DISCOURSE_SMTP_ADDRESS: "smtp-relay.gmail.com" DISCOURSE_SMTP_PORT: 587 DISCOURSE_SMTP_USER_NAME: "user@mydomain.com" DISCOURSE_SMTP_PASSWORD: "mypass" DISCOURSE_SMTP_ENABLE_START_TLS: true DISCOURSE_SMTP_AUTHENTICATION: login DISCOURSE_SMTP_OPEN_TIMEOUT: 25 DISCOURSE_SMTP_READ_TIMEOUT: 25 DISCOURSE_SMTP_DOMAIN: "mydomain.com" DISCOURSE_NOTIFICATION_EMAIL: "noreply@mydomain.com" LETSENCRYPT_ACCOUNT_EMAIL: dev@mydomain.com My Tests When running ./discourse-doctor this configuration leads to the error Testing sending to ... SMTP server connection successful. Sending to artificial.testadress@gmail.com. . . Sending mail failed. end of file reached I then first checked through the different discourse- and email logs Manually testing the same process from within docker (by connecting using docker exec -it bash) via openssl s_client -starttls smtp -crlf -connect smtp.gmail.com:587 encounters no problems and works fine. So I believe either my parameter-configuration in the app.yml is odd OR discourse internally has some script-miscommunication OR … so many possibilities. ^^ To not always have to ./launcher rebuild app after changing app.yml to test different settings I started to directly edit /var/www/discourse/vendor/bundle/ruby/3.2.0/gems/mail-2.8.1/lib/mail/network/delivery_methods/smtp.rb by changing the existing code to: class SMTP attr_accessor :settings DEFAULTS = { :address => 'smtp-relay.gmail.com', :port => 587, :domain => 'mydomain.com', :user_name => 'user@mydomain.com', :password => 'mypass', :authentication => 'login', :enable_starttls => nil, :enable_starttls_auto => true, :openssl_verify_mode => 'peer', :ssl => nil, :tls => nil, :open_timeout => 25, :read_timeout => 25 } def initialize(values) self.settings = DEFAULTS #.merge(values) end which leads to the same behaviour like above (given the customized app.yml) settings. Search for help And now I am stuck. Of course I could play more with the left-over settings (and even could switch back to using SSL-only, even though this is deprecated by discourse), but I’d like to: learn how to analyze this problem deeper and further thereby understand what is really going on and what is the problem fix it and be able to use everything smoothly (+finally get the forum running properly) Thank you for your help in advance.

I’m not sure in regards to Gmail, but Zoho does not work and outlook stopped working on an ecommerce site I was a part of administration on. It’s been best practice to use a transactional email service such as Mailersend for quite a while now but growing more and more a requirement as time goes on. Edit to clarify: it’s a block on the email provider side and not something that can be fixed on Discourse or server side. Most providers no longer support, if they ever even officially did at all, using SMTP to send transactional emails.

SMTP setup not working with GMail's smtp-relay

Product Support Self-hosting

Lou (Lou) March 4, 2026, 6:16pm 5

Has this been resolved? I’m looking to do this exact thing and found this post which is making me nervous.

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SMTP setup not working with GMail's smtp-relay

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