Nochmal zu den Mails:
Du könntest mal versuchen, in includes/functions.inc.php die Zeile

$mail_header_separator = "\r\n"; // try to use "\n" if messages are not sent (see http://php.net/manual/en/function.mail.php)

in

$mail_header_separator = "\n"; // try to use "\n" if messages are not sent (see http://php.net/manual/en/function.mail.php)

zu ändern.

Alex