Cannot receive email via POP3

Product Support

AI-generated summary

schungx reports that their Discourse forum suddenly stopped receiving emails via POP3, despite no configuration changes. The logs show an EmptyEmail exception occurring during email processing, preceded by a network protocol error in net/protocol.rb while retrieving messages. Manual POP3 access via an email client works normally, indicating the issue is specific to Discourse’s email polling job. The stack trace points to failures in poll_mailbox.rb and email/processor.rb, suggesting a problem with how Discourse handles empty or malformed emails during POP3 retrieval. The error appears to originate in the Ruby net-pop library during message download, potentially due to server-side email corruption, malformed headers, or transient network issues. The user seeks help diagnosing why Discourse fails where standard email clients succeed.

1

Suddenly my forum cannot receive any email. It just happened out of the blue. Nothing was changed.

There are the following logs:

activesupport-7.1.4/lib/active_support/broadcast_logger.rb:130:in `block in warn'

activesupport-7.1.4/lib/active_support/broadcast_logger.rb:231:in `block in dispatch'

activesupport-7.1.4/lib/active_support/broadcast_logger.rb:231:in `each'

activesupport-7.1.4/lib/active_support/broadcast_logger.rb:231:in `dispatch'

activesupport-7.1.4/lib/active_support/broadcast_logger.rb:130:in `warn'

/var/www/discourse/lib/email/processor.rb:183:in `log_email_process_failure'

/var/www/discourse/lib/email/processor.rb:29:in `rescue in process!'

/var/www/discourse/lib/email/processor.rb:16:in `process!'

/var/www/discourse/lib/email/processor.rb:13:in `process!'

/var/www/discourse/app/jobs/scheduled/poll_mailbox.rb:29:in `process_popmail'

/var/www/discourse/app/jobs/scheduled/poll_mailbox.rb:49:in `block (2 levels) in poll_pop3'

net-pop-0.1.2/lib/net/pop.rb:669:in `each'

net-pop-0.1.2/lib/net/pop.rb:669:in `each_mail'

/var/www/discourse/app/jobs/scheduled/poll_mailbox.rb:46:in `block in poll_pop3'

net-pop-0.1.2/lib/net/pop.rb:531:in `start'

/var/www/discourse/app/jobs/scheduled/poll_mailbox.rb:45:in `poll_pop3'

/var/www/discourse/app/jobs/scheduled/poll_mailbox.rb:14:in `execute'

/var/www/discourse/app/jobs/base.rb:307:in `block (2 levels) in perform'

rails_multisite-6.1.0/lib/rails_multisite/connection_management/null_instance.rb:49:in `with_connection'
rails_multisite-6.1.0/lib/rails_multisite/connection_management.rb:21:in `with_connection'
/var/www/discourse/app/jobs/base.rb:294:in `block in perform'

/var/www/discourse/app/jobs/base.rb:290:in `each'

/var/www/discourse/app/jobs/base.rb:290:in `perform'

/var/www/discourse/app/jobs/base.rb:361:in `perform'

mini_scheduler-0.17.0/lib/mini_scheduler/manager.rb:137:in `process_queue'

mini_scheduler-0.17.0/lib/mini_scheduler/manager.rb:77:in `worker_loop'

mini_scheduler-0.17.0/lib/mini_scheduler/manager.rb:63:in `block (2 levels) in ensure_worker_threads'

It throws an EmptyEmail exception…

Manually connecting to the email account via POP3 using a regular email app works just fine.

An error preceeds this error in the log:

/usr/local/lib/ruby/3.3.0/net/protocol.rb:237:in `rbuf_fill'
/usr/local/lib/ruby/3.3.0/net/protocol.rb:199:in `readuntil'
/usr/local/lib/ruby/3.3.0/net/protocol.rb:377:in `each_message_chunk'
net-pop-0.1.2/lib/net/pop.rb:958:in `block in retr'

net-pop-0.1.2/lib/net/pop.rb:1016:in `critical'

net-pop-0.1.2/lib/net/pop.rb:956:in `retr'

net-pop-0.1.2/lib/net/pop.rb:810:in `pop'

/var/www/discourse/app/jobs/scheduled/poll_mailbox.rb:47:in `block (2 levels) in poll_pop3'

net-pop-0.1.2/lib/net/pop.rb:669:in `each'

net-pop-0.1.2/lib/net/pop.rb:669:in `each_mail'

/var/www/discourse/app/jobs/scheduled/poll_mailbox.rb:46:in `block in poll_pop3'

net-pop-0.1.2/lib/net/pop.rb:531:in `start'

/var/www/discourse/app/jobs/scheduled/poll_mailbox.rb:45:in `poll_pop3'

/var/www/discourse/app/jobs/scheduled/poll_mailbox.rb:14:in `execute'

/var/www/discourse/app/jobs/base.rb:307:in `block (2 levels) in perform'

rails_multisite-6.1.0/lib/rails_multisite/connection_management/null_instance.rb:49:in `with_connection'
rails_multisite-6.1.0/lib/rails_multisite/connection_management.rb:21:in `with_connection'
/var/www/discourse/app/jobs/base.rb:294:in `block in perform'

/var/www/discourse/app/jobs/base.rb:290:in `each'

/var/www/discourse/app/jobs/base.rb:290:in `perform'

/var/www/discourse/app/jobs/base.rb:361:in `perform'

mini_scheduler-0.17.0/lib/mini_scheduler/manager.rb:137:in `process_queue'

mini_scheduler-0.17.0/lib/mini_scheduler/manager.rb:77:in `worker_loop'

mini_scheduler-0.17.0/lib/mini_scheduler/manager.rb:63:in `block (2 levels) in ensure_worker_threads'