Windows Live Mail has recently stopped sending e-mails, leaving them in the Outbox. I receive the following error message every time.

An unknown error has occurred.

Subject 'Test'
Server: 'smtp.ox.ac.uk'
Windows Live Mail Error ID: 0x800CCC0B
Protocol: SMTP
Port: 25
Secure(SSL): Yes

Following advice I have found elsewhere, I have tried:

• changing the outgoing port from 25 to 465
• changing the outgoing port from 25 to 587
• repairing Windows Live Mail
• removing and the reinstalling my account
• checking that the "my server requires authentication" box is ticked

All this has been to no avail.

Any further suggestions much appreciated.