Description:
------------
It is very possible for a developer to use code like in the attached reproduction code to send an e-mail. However, when mail.add_x_header is On, using this code will cause the X-PHP-Originating-Script to show in the message body instead of as a header. 

This is because mail() assumes the $headers parameter is a string which does not end with a trailing CRLF - while in practice it very well may be (it works well when mail.add_x_header is Off). 




Reproduce code:
---------------
<?php

$headers = array(
	'X-Foo' => 'bar',
	'From' => 'some-guy@example.com',
	'Priority' => 'Urgent'
);

$hdrStr = '';
foreach($headers as $k => $v) {
	$hdrStr .= "$k: $v\r\n";
}

mail('someone-else@example.com', 
     'Testing add_x_header', 
     'This is a test', 
     $hdrStr);


Expected result:
----------------
Mail to look like:
                                                                                                                                                                                                                                                               
To: someone-else@example.com
Subject: Testing add_x_header
X-Foo: bar
From: some-guy@example.com
Priority: Urgent
Date: Sat, 20 Jun 2009 20:37:34 +0300 (IDT)
X-PHP-Originating-Script: 503:mailtest.php

This is a test


Actual result:
--------------
To: someone-else@example.com
Subject: Testing add_x_header
X-Foo: bar
From: some-guy@example.com
Priority: Urgent
Date: Sat, 20 Jun 2009 20:37:34 +0300 (IDT)

X-PHP-Originating-Script: 503:mailtest.php

This is a test



* this is how I receive the e-mail in GMail - perhaps there is some header mangling but you get the point