Help with PHP send() - Not reaching Hotmail

[infusionstudios]

I've been sending newsletters off my server's send() mail command in php for some time (years). All but recently, we've been running into some huge problems with Hotmail.com accounts receiving our emails.

 

1) It's not with the newsletters we send. I dummied the php script down to this:

<?

$to      = emailaddress@hotmail.com';

$subject = 'the subject';

$message = 'hello';

$headers = 'From: my@domain.com' . "\r\n" .

'Reply-To: my@domain.com' . "\r\n" .

'X-Mailer: PHP/' . phpversion();

mail($to, $subject, $message, $headers);

?>

And it still does not work.

2) It's not getting put in junk email folders on Hotmail

3) I am not getting any type of bounce back or error messages

 

However, if I send a email using outlook from my@domain.com, it does reach Hotmail (just goes into junk email folder).

 

I created the SPF records, made sure my DNS was correct - what seems to be the problem?