Try running cmclean.sql script.
Please have a look links:
Hope this helps!
Please post the details of the application release, database version and OS.
Please see the following docs.
Java Notification Mailer Fails to Send Email Notifications with Framework Regions (Doc ID 339718.1)
Notifications With Embedded Framework Regions Are Not Mailed or Sent (Doc ID 309856.1)
Troubleshooting Inbound & Outbound Email Notifications (Doc ID 1184846.1)
Workflow Mailer not Sending Notifications java.net.ConnectException: Connection refused (errno:239) (Doc ID 972161.1)
Not Receiving Workflow Email Notifications Possible Connection Refused Error (Doc ID 464016.1)
Connection Refused Errors in Mailer Log After Applying ATG RUP4 (Doc ID 403431.1)