We recently had a problem trying to send email using the PHP Mail function on Windows 2003 Server. When we tried to send mail we just got an error message:

PHP Warning: mail(): SMTP server response: 501 5.5.4 Invalid Address

We were trying to add a ‘friendly’  name to the from header of the email in the format: 

$headers .= ‘From:  Name ’. “\r\n”;

We found that PHP running on Windows doesn’t parse these headers correctly (see http://www.php.net/manual/en/function.mail.php ) so the fix was to change to:

$headers .= ‘From:  address@domain.com’. “\r\n”;

Which gets the mail to send but doesn’t allow us to use ‘friendly’ names.