Verify that email domain exists

Question

Does anyone check the domain of an email address as part of their verification steps? eg. Confirm that gmail.com exists if the user specified blah@gmail.com as their address

Answer 1

You could execute this command in the console

 nslookup -q=mx gmail.com

and parse the output for rows containing MX after the hostname

gmail.com       MX preference = 40, mail exchanger = alt4.gmail-smtp-in.l.google.com
gmail.com       MX preference = 20, mail exchanger = alt2.gmail-smtp-in.l.google.com
gmail.com       MX preference = 5, mail exchanger = gmail-smtp-in.l.google.com
gmail.com       MX preference = 30, mail exchanger = alt3.gmail-smtp-in.l.google.com
gmail.com       MX preference = 10, mail exchanger = alt1.gmail-smtp-in.l.google.com

But I wouln't recommend this kind of check in the first place. If a user doesn't want to give you his e-mail address he will always find a way to trick you. The only think you can do is send an email with a verification link.