I can send mail through SMTP using outlook without any problems. The problems come in when sending an automated email through our shopping cart via PHP. Diagnostic-Code: X-Postfix; host relay.verizon.net[188.8.131.52] said: 550 You are not allowed to send mail:sv22pub.verizon.net (in reply to MAIL FROM command) Received: from server.myserver.com (server.myserver.com [127.0.0.1]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by www.myserver.com (Postfix) with ESMTP id C869E1CCB96 for <[email protected] Received: (from [email protected] by server.myserver.com (8.13.1/8.13.1/Submit) id l24E1Mu1009247; Sun, 4 Mar 2007 09:01:22 -0500 I assumed this is because of the server name and attempted to change the name in /etc/hostname and using /bin/hostname -F /etc/hostname. That worked fine until reboot and the it changed back to server.myserver.com. Also, it could have been the (from [email protected] Any ideas why the server name would change back? Any ideas on an overall fix?