Trying to set up email using comcast.net account. Have successfully received email, but cannot send. I get this error message:

The connection to the server has failed.

Subject 'test'
Server: 'smtp.comcast.net'
Windows Live Mail Error ID: 0x800CCC0E
Protocol: SMTP
Port: 25
Secure(SSL): No
Socket Error: 10060

I have tried deleting email account and re-adding. I have tried repairing Windows Essentials, I have talked to ISP tech support. This is Windows 7, by the way.