FEATURE: admin dashboard check when email polling errored in the past 24 hours

app/jobs/scheduled/poll_mailbox.rb

@@ -80,6 +80,7 @@ module Jobs
 
         client_message
       else
+        mark_as_errored!
         Discourse.handle_job_exception(e, error_context(@args, "Unrecognized error type when processing incoming email", mail: mail_string))
       end
     end
@@ -94,8 +95,21 @@ module Jobs
         end
       end
     rescue Net::POPAuthenticationError => e
+      mark_as_errored!
       Discourse.handle_job_exception(e, error_context(@args, "Signing in to poll incoming email"))
     end
 
+    POLL_MAILBOX_ERRORS_KEY ||= "poll_mailbox_errors".freeze
+
+    def self.errors_in_past_24_hours
+      $redis.zremrangebyscore(POLL_MAILBOX_ERRORS_KEY, 0, 24.hours.ago.to_i)
+      $redis.zcard(POLL_MAILBOX_ERRORS_KEY).to_i
+    end
+
+    def mark_as_errored!
+      now = Time.now.to_i
+      $redis.zadd(POLL_MAILBOX_ERRORS_KEY, now, now.to_s)
+    end
+
   end
 end

app/models/admin_dashboard_data.rb

@@ -63,7 +63,7 @@ class AdminDashboardData
                       :send_consumer_email_check, :title_check,
                       :site_description_check, :site_contact_username_check,
                       :notification_email_check, :subfolder_ends_in_slash_check,
-                      :pop3_polling_configuration
+                      :pop3_polling_configuration, :email_polling_errored_recently
 
     add_problem_check do
       sidekiq_check || queue_size_check
@@ -210,4 +210,9 @@ class AdminDashboardData
     POP3PollingEnabledSettingValidator.new.error_message if SiteSetting.pop3_polling_enabled
   end
 
+  def email_polling_errored_recently
+    errors = Jobs::PollMailbox.errors_in_past_24_hours
+    I18n.t('dashboard.email_polling_errored_recently', count: errors) if errors > 0
+  end
+
 end

config/locales/server.en.yml

@@ -781,6 +781,9 @@ en:
     site_contact_username_warning: "Enter the name of a friendly staff user account to send important automated messages from. Update site_contact_username in <a href='/admin/site_settings'>Site Settings</a>."
     notification_email_warning: "Notification emails are not being sent from a valid email address on your domain; email delivery will be erratic and unreliable. Please set notification_email to a valid local email address in <a href='/admin/site_settings'>Site Settings</a>."
     subfolder_ends_in_slash: "Your subfolder setup is incorrect; the DISCOURSE_RELATIVE_URL_ROOT ends in a slash."
+    email_polling_errored_recently:
+      one: "Email polling has generated an error in the past 24 hours. Look at <a href='/logs' target='_blank'>the logs</a> for more details."
+      other: "Email polling has generated %{count} errors in the past 24 hours. Look at <a href='/logs' target='_blank'>the logs</a> for more details."
 
   site_settings:
     censored_words: "Words that will be automatically replaced with &#9632;&#9632;&#9632;&#9632;"