I am developing an application and have been testing the mail() function in PHP. The following works just fine on my local machine to send emails to myself, but as soon as I try to send it from the testing environment to my local machine, it silently fails. I will still get the "Mail Sent" message, but no message is sent. I turned on the mail logging in the php.ini file, but even that doesn't seem to be populated after I refresh the page. Again, the .php files and php.ini files are identical in both environments. Port 25 has been opened on the testing environment, and we are using a Microsoft Exchange server. <?php $to = "[email protected]"; $subject = "Test mail"; $message = "Hello! This is a simple email message."; $from = "[email protected]"; $headers = "From:" . $from; mail($to,$subject,$message,$headers); echo "Mail Sent."; ?> SMTP area of the php.ini file: [mail function] ; For Win32 only. ; http://php.net/smtp SMTP = exhange.server.org ; http://php.net/smtp-port smtp_port = 25 ; For Win32 only. ; http://php.net/sendmail-from sendmail_from = [email protected]