PHPmailer sending mail to spam in hotmail. how to fix?

Question

I'm using the phpmailer class to send emails. Currently gmail and yahoo do not mark emails as spam, but hotmail always does. How can I prevent this? My code is below.

require_once('../PHPMailer/class.phpmailer.php');
//include("class.smtp.php"); // optional, gets called from within class.phpmailer.php if not already loaded

$mail = new PHPMailer();

$mail->IsSMTP();    // set mailer to use SMTP
$mail->Host = "mail.example.com";    // specify main and backup server
$mail->SMTPAuth = true;    // turn on SMTP authentication
$mail->Username = "xxx";    // SMTP username -- CHANGE --
$mail->Password = "xxx";    // SMTP password -- CHANGE --
$mail->Port = "25";    // SMTP Port

$mail->From = "no-repy@example.com";    //From Address -- CHANGE --
$mail->FromName = "xxx";    //From Name -- CHANGE --
$mail->AddAddress($email, $passerusername);    //To Address -- CHANGE --
$mail->AddReplyTo("no-reply@example.com", "xxx"); //Reply-To Address -- CHANGE --

$mail->WordWrap = 50;    // set word wrap to 50 characters
$mail->IsHTML(false);    // set email format to HTML

$mail->Subject = "AuthSMTP Test";
$mail->Body    = "AuthSMTP Test Message!";

if(!$mail->Send())
{
   echo "Message could not be sent. <p>";
   echo "Mailer Error: " . $mail->ErrorInfo;
   exit;
}

echo "Message has been sent";

Answer 1

This involves setting a few mail headers to beat the filters.

I have added the following to the very start of php mailers CreateHeader method...

$result = '';

$result .= $this->HeaderLine("Organization" , SITE); 
$result .= $this->HeaderLine("Content-Transfer-encoding" , "8bit");
$result .= $this->HeaderLine("Message-ID" , "<".md5(uniqid(time()))."@{$_SERVER['SERVER_NAME']}>");
$result .= $this->HeaderLine("X-MSmail-Priority" , "Normal");
$result .= $this->HeaderLine("X-Mailer" , "Microsoft Office Outlook, Build 11.0.5510");
$result .= $this->HeaderLine("X-MimeOLE" , "Produced By Microsoft MimeOLE V6.00.2800.1441");
$result .= $this->HeaderLine("X-Sender" , $this->Sender);
$result .= $this->HeaderLine("X-AntiAbuse" , "This is a solicited email for - ".SITE." mailing list.");
$result .= $this->HeaderLine("X-AntiAbuse" , "Servername - {$_SERVER['SERVER_NAME']}");
$result .= $this->HeaderLine("X-AntiAbuse" , $this->Sender);

that was done some time ago - I haven't revisited for about a year I think! Try it and come back if you still have problems.