|You said "When ever I try to send an email..."|
Does "an email" mean a specific email that is giving you problems or does every email pop up the error?
Does the message have a title or something that says who is sending the error message?
Who supports your out-going email? If you can't send, even to yourself, then it's possible that your own ISP or mail-server thinks you are sending spam. Have you contacted their technical support staff?
Are you using a mail client (Thunderbird, Outlook, etc.) or a web-based mail app (Yahoo, etc.) I use Thunderbird, but I can also send and recieve from the same address using my provider's web-based email site. If you can do that, have you tried it both ways?
I'm just tossing out some troubleshooting steps to help narrow it down...