Can you please copy and paste the entire error message as a reply to this thread?
Is it an bounce message that you get back in your e-mail, or a popup box error when you try to send a new e-mail?
I will be able to give you the best answer for the problem if we can see the exact error message.
Also, how are you trying to send the e-mail (comcast webmail or a program on your computer) and the name of the program you are using, for example, Microsoft Outlook.
The host 'comcast' could not be found. Please verify that you have entered the server name correctly.
Subject 'how's business?', Account: 'comcast', Server: 'comcast', Protocol: SMTP, Port: 25, Secure(SSL): No, Socket Error: 11001, Error Number: 0x800CCC0D
It sounds like you entered the wrong outgoing mail server (SMTP) server name in your e-mail account settings.
In your e-mail program, check your server settings, and replace comcast with smtp.comcast.net.
In Outlook Express you can use screen shots from our how to leave a copy of messages on the server guide, but go to the Servers tab instead of the Advanced tab and check the SMTP outgoing mail server setting on that page.