Simple spam check for valid domain in commenter's email address

Question

Many times commenters leave fabricated email addresses. As a really basic step, is there a plugin that checks to make sure that the domain actually exists?

Answer 1

The problem is not if it exists, after all I can sign up with jnm2.2mnj@yahoo.com , it's fake and the domain obviously exists.

The only real way to verify is to send an email to the address and have an action that they click.