use strict;
use IO::Socket;

my $sock = IO::Socket::INET->new(
   PeerAddr => '127.0.0.1',
   PeerPort => '25',
   Proto    => 'tcp',
   Type     => SOCK_STREAM
);

do_mail($sock);
print $sock "quit\n";
close($sock);

sub do_mail {
   my($handle) = shift;

   my $buf = <$handle>;

   print "Sendmail ", $buf ? "is OK\n" : "is not responding\n";

}