Has this ever worked before or is this the first time using Outlook Express with this email?
This might be just that you have your outgoing mail server(SMTP) set wrong. This should be set to your ISP(INternet Service Provider) SMTP server address.
For example Medicom Cable SMTP server is mail.mchsi.com even though my school recommends to use their SMTP server on their setup page. This is due to most ISP's not allowing "relaying" through them to another SMTP server. Some ISP require you to use your login info as well to verify who you are when you send mail through them.
See if that works, if not get back to us.
Also you might find that an email client such as Thunderbird is more robust and functional then Outlook Express. This can be found at:http://www.mozilla.o...ts/thunderbird/