<p>Looking for an example in linq about how to insert a row of a gridview into datacontext. </p>

That was asked
here
a couple of weeks ago. What it comes down to is, there are many legal addresses that an easy regex won't match. It takes a truly insane regex to match the majority of legal addresses. And even then, a syntactically legal address doesn't guarantee the existence of an account behind it - take foo@example.invalid, for example.