This is the error I am receiving how can I fix it?

Unable to send or receive messages for the Andrea account. Your server has unexpectedly terminated the connection. Possible causes for this include server problems, network problems, or a long period of inactivity.

Server: 'pop.att.yahoo.com'
Windows Live Mail Error ID: 0x800CCC0F
Protocol: POP3
Port: 995
Secure(SSL): Yes