When I try to log in whith a wrong password I also get this messege:
Warning: Cannot modify header information - headers already sent by (output started at /home/admispconfig/ispconfig/web/webmail/inc/class.uebimiau_mail.php:61) in /home/admispconfig/ispconfig/web/webmail/msglist.php on line 65
This change I've already done:
header("Content-Type: $content_type; name=\"$filename\"");
I'm using the latest release of uebimiau_mail, ISPConfig 2.2.1 and the latests release of firefox.