Zammad Email Issue

Technical assistance
1

Infos:

  • Used Zammad version:
  • Used Zammad installation type: (source, package, docker-compose, …)
  • Operating system:
  • Browser + version:

We are facing SMTP email authentication failure but eventhough it succeeds and below are the logs. Please help

Getting below error suddenly in Zammad and outbound email authentication not working

{“log”:“E, [2025-12-19T17:06:41.010984#1-183980] ERROR – : Can’t use Channel::Driver::Smtp: #\u003cNet::SMTPAuthenticationError: Net::SMTPAuthenticationError\u003e\n”,“stream”:“stdout”,“time”:“2025-12-19T11:36:41.01114667Z”}

{“log”:“E, [2025-12-19T17:06:41.423472#1-183980] ERROR – : 2025-12-19T17:06:41+0530: [Worker(host:6b9d13e2a441 pid:1)] Job TicketArticleCommunicateEmailJob [b907c80a-e390-4764-914a-e14938548eb0] from DelayedJob(default) with arguments: [515843] (id=3299172) (queue=default) FAILED (3 prior attempts) with RuntimeError: Can’t use Channel::Driver::Smtp: #\u003cNet::SMTPAuthenticationError: Net::SMTPAuthenticationError\u003e\n”,“stream”:“stdout”,“time”:“2025-12-19T11:36:41.423579587Z”}

{“log”:“E, [2025-12-19T17:06:41.423536#1-183980] ERROR – : 2025-12-19T17:06:41+0530: [Worker(host:6b9d13e2a441 pid:1)] Job TicketArticleCommunicateEmailJob [b907c80a-e390-4764-914a-e14938548eb0] from DelayedJob(default) with arguments: [515843] (id=3299172) (queue=default) FAILED permanently because of 4 consecutive failures\n”,“stream”:“stdout”,“time”:“2025-12-19T11:36:41.423598407Z”}

{“log”:“I, [2025-12-19T17:06:41.428490#1-183980] INFO – : 2025-12-19T17:06:41+0530: [Worker(host:6b9d13e2a441 pid:1)] Job TicketArticleCommunicateEmailJob [1ccd818f-7695-4966-8e30-9a44bdc474c6] from DelayedJob(default) with arguments: [515845] (id=3299173) (queue=default) RUNNING\n”,“stream”:“stdout”,“time”:“2025-12-19T11:36:41.428574138Z”}

{“log”:“E, [2025-12-19T17:06:42.265305#1-183980] ERROR – : Can’t use Channel::Driver::Smtp: #\u003cNet::SMTPAuthenticationError: Net::SMTPAuthenticationError\u003e\n”,“stream”:“stdout”,“time”:“2025-12-19T11:36:42.265424847Z”}

{“log”:“E, [2025-12-19T17:06:42.265377#1-183980] ERROR – : 334 eyJzdGF0dXMiOiI0MDAiLCJzY2hlbWVzIjoiQmVhcmVyIiwic2NvcGUiOiJodHRwczovL21haWwuZ29vZ2xlLmNvbS8ifQ==\n”,“stream”:“stdout”,“time”:“2025-12-19T11:36:42.265778895Z”}

{“log”:" (Net::SMTPAuthenticationError)\n",“stream”:“stdout”,“time”:“2025-12-19T11:36:42.265788845Z”}

{“log”:“lib/core_ext/net/smtp.rb:47:in `do_start’\n”,“stream”:“stdout”,“time”:“2025-12-19T11:36:42.265793275Z”}

{“log”:“app/models/channel/driver/smtp.rb:98:in `deliver’\n”,“stream”:“stdout”,“time”:“2025-12-19T11:36:42.265796795Z”}

{“log”:“app/models/channel.rb:266:in `deliver’\n”,“stream”:“stdout”,“time”:“2025-12-19T11:36:42.265800236Z”}

{“log”:“app/jobs/ticket_article_communicate_email_job.rb:56:in `perform’\n”,“stream”:“stdout”,“time”:“2025-12-19T11:36:42.265803685Z”}

{“log”:“lib/background_services/service/process_delayed_jobs.rb:25:in `block (2 levels) in launch’\n”,“stream”:“stdout”,“time”:“2025-12-19T11:36:42.265813056Z”}

{“log”:“lib/background_services/service/process_delayed_jobs.rb:23:in `block in launch’\n”,“stream”:“stdout”,“time”:“2025-12-19T11:36:42.265816776Z”}

{“log”:“lib/background_services/service/process_delayed_jobs.rb:20:in `loop’\n”,“stream”:“stdout”,“time”:“2025-12-19T11:36:42.265832516Z”}

{“log”:“lib/background_services/service/process_delayed_jobs.rb:20:in `launch’\n”,“stream”:“stdout”,“time”:“2025-12-19T11:36:42.265836396Z”}

{“log”:“lib/background_services/service.rb:27:in `block in run’\n”,“stream”:“stdout”,“time”:“2025-12-19T11:36:42.265839896Z”}

{“log”:“lib/application_handle_info.rb:19:in `use’\n”,“stream”:“stdout”,“time”:“2025-12-19T11:36:42.265843526Z”}

{“log”:“lib/background_services/service.rb:33:in `block in run_in_service_context’\n”,“stream”:“stdout”,“time”:“2025-12-19T11:36:42.265846926Z”}

{“log”:“lib/background_services/service.rb:32:in `run_in_service_context’\n”,“stream”:“stdout”,“time”:“2025-12-19T11:36:42.265850306Z”}

{“log”:“lib/background_services/service.rb:26:in `run’\n”,“stream”:“stdout”,“time”:“2025-12-19T11:36:42.265853687Z”}

{“log”:“lib/background_services.rb:71:in `block in start_as_thread’\n”,“stream”:“stdout”,“time”:“2025-12-19T11:36:42.265857277Z”}

{“log”:“E, [2025-12-19T17:06:42.363050#1-183980] ERROR – : Can’t use Channel::Driver::Smtp: #\u003cNet::SMTPAuthenticationError: Net::SMTPAuthenticationError\u003e\n”,“stream”:“stdout”,“time”:“2025-12-19T11:36:42.363174688Z”}

SMTP Authentication Error in UI:

#<Net::SMTPAuthenticationError: Net::SMTPAuthenticationError>