Utility to verify an email address

 Mail::Verify provides a function CheckAddress function for verifying
 email addresses. First the syntax of the email address is checked, then
 it verifies that there is at least one valid MX server accepting email
 for the domain. Using Net::DNS and IO::Socket a list of MX records (or,
 falling back on a hosts A record) are checked to make sure at least one
 SMTP server is accepting connections.