use strict;
use warnings;
use Net::SMTP;

my $smtp = Net::SMTP->new('MAILSERVER') or die $!;

my ($from, $to) = ('blah@domain.com', 'user@otherdomain.com');
my ($subject, $message) = ('Test subject', 'Test message');

$smtp->mail( $from );
$smtp->to( $to );
$smtp->data();
$smtp->datasend("To: $to\n");
$smtp->datasend("From: $from\n");
$smtp->datasend("Subject: $subject\n");
$smtp->datasend("\n"); # done with header
$smtp->datasend($message);
$smtp->dataend();
$smtp->quit(); # all done. message sent.