I see in the Admin panel that we have email problems:
Some problems have been found with your installation of Discourse:
There are 26537 email jobs that failed. Check your app.yml and ensure that the mail server settings are correct. See the failed jobs in Sidekiq.
In Sidekiq, I see all of the errors are
Jobs::HandledExceptionWrapper: Wrapped Net::SMTPAuthenticationError: 535 5.7.0 message limit reached