HELP! Receiving, but can't send email

This is the blasted error message that I am getting now. I have changed nothing in my accounts' properties, yet a few days ago, Windows Mail just decided to stop sending my mail.

I use a POP account (yahoo) on my laptop which I use wirelessly. If any of that matters.

Thank you in advance for your assistance!!

Trish

Here's the message

The connection to the server has failed. Subject 'Re: Re: Re: Re: Fwd: Message submitted from Cousin's Online Form', Account: 'pop.mail.yahoo.com', Server: 'smtp.mail.yahoo.com', Protocol: SMTP, Port: 25, Secure(SSL): No, Socket Error: 10013, Error Number: 0x800CCC0E