NAME
    Mail::EXPN - Perl extension for validation of email addresses

SYNOPSIS
      use Mail::EXPN qw(isfake);

      $reason = isfake('bill@microsoft.com');
      if ($reason) {
        print "Bad email: $reason\n";
      } elsif (defined($reason)) {
        print "Email address perfect\n";
      } else {
        print "Could not verify email address: EXPN is turned off at target computer";
      }

      $reason = isfake('bigboss', 'mail.acme.com');
      ...

DESCRIPTION
    This module checks validity of email addresses. It ensure the existence
    of a username and domain, unless you specified the MTA, searches the DNS
    for the MTA (if not specified), and then attempts to use the SMTP
    keyword EXPN to verify the username. Since EXPN is usually turned off,
    the module will return *undef* in such cases, and defined but false if
    the verification passed. If for any reason the check failed, the module
    will return a string describing the reason.

CAVEATS
    Contemporary ISPs never turn EXPN on, to prevent mail abusers harass
    more efficiently by molesting only existing addresses with junk mail.
    Therefore, this is not an excellent solution to check the fill-out forms
    in your site for users supplying false email addresses. Most addresses
    associated with valid MTAs will return *undef*.

NOTE ON RFC 2821
    Mail::EXPN only checks the first mx specified, as it is likely to be the
    only one to contain the user list.

TO DO
    I tried to rewrite the module using Net::SMTP, but could not figure how
    to handle the expand and verify methods. They seemed to return an empty
    reply.

CREDITS
    Idea by Raz Information Systems, http://www.raz.co.il.

AUTHOR
    Ariel Brosh, schop@cpan.org.

MAINTAINER
    Florian Helmberger, florian@cpan.org.

VERSION
    $Id: README,v 1.2 2003/02/01 10:45:49 florian Exp $

SEE ALSO
    perl(1).