I have written an article for that,
Sending emails easily using ASP.NET helpers[
^]
You can read that and remember, you can send email to any address from any address. All you need to care about is the credentials that you provide.
Since you're using ASP.NET, the article I have written explains it all, you can use the built-in
WebMail
class and pass on your username, password and then send the email to who ever you want to on the Internet.