Layton ServiceDesk - Troubleshooting - Outgoing Email Stops
From Layton Support
Usually this is due to unusual characters in an email. If outgoing mail ever stops, here is the immediate remedy:
1. Go to Administration > System Settings > Email Server Settings.
2. Click the View Pending Outgoing Emails link.
3. A list of outgoing emails will appear:
4. Here you can see that the earliest email could not be sent. Click the Delete button for that email and confirm. The rest of the emails should now be sent. If not, you can delete the now-earliest. Don't delete more than three emails, as this could indicate a different issue, most likely a misconfiguration of email settings.