perl-Mail-RFC822-Address -- Perl extension for validating email addresses according to RFC822
http://search.cpan.org/dist/Mail-RFC822-Address/
Mail::RFC822::Address validates email addresses against the grammar
described in RFC 822 using regular expressions. The only sure way to
see if a supplied email address is genuine is to send an email to it
and see if the user recieves it. This package only checks that the email
address is syntactically valid.