Symptom

When you start Outlook Express or try to send an e-mail message, you may see the following error message:

Your server has unexpectedly terminated the connection. Possible causes for this include server problems, network problems, or a long period of inactivity. Account: ‘mail.example.com’, Server: ‘mail.example.com’, Protocol: POP3, Port: 110, Secure(SSL): No, Error Number: 0x800CCC0F

Resolution

First check all your settings are correct by running through this article on setting up Outlook to access your email using POP3:

Next, if you are running Norton or Symantec security products then disable the email protection feature in these products as it is known to cause this error. Your email account includes an advanced virus scanner as standard so you will still be protected from viruses.