Even if you clean up personal information, you should still post code that will run. Also, be sure to post the entire error message. Did you delete the content you're assigning to 'Hello'? That would yield something like the error you mention in your reply. It should do a decent job of picking a helo line for you.

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

$host = "mail.host.com";
$port = 25;

$smtp = Net::SMTP->new($host, port=>$port);
$smtp->mail("test\@domain.com");
$smtp->recipient("test\@domain2.com");
$smtp->data;
$smtp->datasend("From: test\@domain.com");
$smtp->datasend("To: test\@domain2.com");  
$smtp->datasend("Subject: Test");
$smtp->datasend("\n");
$smtp->datasend ("This is a test");

$smtp->dataend;
$smtp->quit;
[download]