test mail_reminder get IMAP error

[jameswangcnln78]

I installed redmine_mail_reminder in Redmine 3.4.2 and tested it and got the following error in cron_rake.log:

rake aborted! SSL_connect returned=1 errno=0 state=unknown state: unknown protocol /home/redmine/redmine/lib/redmine/imap.rb:30:in new' /home/redmine/redmine/lib/redmine/imap.rb:30:in check' /home/redmine/redmine/lib/tasks/email.rake:117:in block (4 levels) in <top (required)>' /home/redmine/redmine/app/models/mailer.rb:433:in with_synched_deliveries' /home/redmine/redmine/lib/tasks/email.rake:116:in `block (3 levels) in <top (required)>' Tasks: TOP => redmine:email:receive_imap (See full trace by running task with --trace)

The command I used is "sudo docker exec -it redmine-app bundle exec rake reminder:exec[test] RAILS_ENV=production --trace". And it seemed no error reported

** Invoke reminder:exec (first_time) ** Invoke environment (first_time) ** Execute environment ** Execute reminder:exec

I wonder why IMAP code got running?

Any help will be appreciated!

James