Php's mail double-ing up on new lines - php

Question

For some reason in php when sending a "multipart/alternative" email it seems to double-up new lines messing up the formatting for plain-text clients.
Here's my code:
$boundary = uniqid('np');
// To send HTML mail, the Content-type header must be set
$headers = 'MIME-Version: 1.0' . "\r\n";
$headers .= "Content-Type: multipart/alternative;charset=utf-8;boundary=" . $boundary . "\r\n";
$headers .= "From: GamingOnLinux.com Notification <noreply#gamingonlinux.com>\r\n" . "Reply-To: noreply#gamingonlinux.com\r\n";
$message .= "\r\n\r\n--" . $boundary . "\r\n";
$message .= "Content-Type: text/plain;charset=utf-8\r\n";
$message .= "Content-Transfer-Encoding: 7bit\r\n";
$message .= $plain_message;
$message .= "\r\n\r\n--" . $boundary . "\r\n";
$message .= "Content-Type: text/html;charset=utf-8\r\n";
$message .= "Content-Transfer-Encoding: 7bit\r\n";
$message .= "$html_message";
$message .= "\r\n\r\n--" . $boundary . "--";
// Mail it
mail($to, $subject, $message, $headers);
So it ends up coming out like this:
--np53494d20d247e
Content-Type: text/plain;charset=utf-8
Content-Transfer-Encoding: 7bit
When there should be no line between them?

Answer 1

You are currently using MS-Windows style line endings (\r\n). Use Unix style line endings instead (\n) and most likely your issue is solved.
Different systems traditionally encode line ending different. But the unixoid version is the one which probably can be considered the "internet native style", since the internet (thus all network exchange stuff) was developed based on unixoid systems. Actually things were more complex, this obviously is a simplification. Therefore most (at least all sane) clients like email programs should be able to handle and disply such line ending correctly, whilst the MS-Windows style looks "funny" to many of them.