Why my mails are not received by Hotmail users?

Hi. I created this script to send emails: ------------------- $mailFromEmail = "info@mydomain.com"; $mailFromName = "MYDOMAIN"; $mailTo = "jack@gmail.com"; $mailHeaders = "From: $mailFromName <$mailFromEmail>\n" . "Content-Type: text/plain; " . "charset=UTF-8; format=flowed\n" . "MIME-Version: 1.0\n" . "Content-Transfer-Encoding: 8bit\n"; $mailSubject = "Hi! " . date('h:i:s A'); $mailMessage = "Hi,\n\nHow are you?\n" . date('l dS \of F Y h:i:s A') . "\n"; mail($mailTo, $mailSubject, $mailMessage, $mailHeaders); ------------------- In addition, I've set an SPF policy on my DNS server, and I added this line to my 'php.ini' file: ------------------- sendmail_path = /usr/sbin/sendmail -t -i -f info@mydomain.com ------------------- (I've got 'safe_mode=on' on my server) So Gmail users receive the messages correctly: ------------------- Delivered-To: jack@gmail.com Received: by 10.100.121.18 with SMTP id t18cs105671anc; Fri, 4 Apr 2008 06:58:23 -0700 (PDT) Received: by 10.114.56.1 with SMTP id e1mr1995521waa.52.1207317502773; Fri, 04 Apr 2008 06:58:22 -0700 (PDT) Return-Path: <info@mydomain.com> Received: from v2v-3.net ([52.147.120.136]) by mx.google.com with ESMTP id q18si8099195pog.7.2008.04.04.06.58.22; Fri, 04 Apr 2008 06:58:22 -0700 (PDT) Received-SPF: pass (google.com: domain of info@mydomain.com designates 52.147.120.136 as permitted sender) client-ip=52.147.120.136; Authentication-Results: mx.google.com; spf=pass (google.com: domain of info@mydomain.com designates 52.147.120.136 as permitted sender) smtp.mail=info@mydomain.com Received: (qmail 21817 invoked by uid 48); 4 Apr 2008 06:58:22 -0700 ------------------- Note the "Return-Path" line and the "Received-SPF" line. If I change 'jack@gmail.com' with 'jack@hotmail.com', they don't receive my emails. What am I doing wrong?