Description:
------------
If mail() is called with the $header argument, an empty line is inserted before the $header ĺine. Therefore the content of $header is not seen as valid mail header.



Test script:
---------------
<?php

$crlf = chr(13) . chr(10);

$to      = "me@example.com";
$subject = "my subject";
$body1   = "my body -- with header";
$body2   = "my body -- no header";
$header  = "From: you@example.com${crlf}".
           "X-Mailer: PHP/" . phpversion() . $crlf;

$res1 = mail ($to, $subject, $body1, $header);
$res2 = mail ($to, $subject, $body2);

printf ("mail res=${res1}; ${res2}\n");
?>

Actual result:
--------------
If $header is given (see example above) the (shortened) mail text looks like:
---------------------------  from here
Return-Path: <....>
Received: ....
To: me@example.com
Subject: my sub
X-Mailer: PHP/5.3.1
Message-Id: <...>
From: ...
Message-Id: <...>
Date: ...
X-Length: 2014
X-UID: 252148

Message-Id: <...>
Date: ....
From: ....


my body -- with header1
---------------------- to here

Now After X-UID: there is an empty line, which should n ot be there (in my opinion).