Horde not working, system is Plesk 8.6.0 with Windows 2008 Server Web.
Something similar to the link below but I have no clue of how to change it on 8.6. According to the IIS settings of the webmail(horde)-site Horde is already using the Handler pointing to %pleskdir%\additional\php\php.exe, which is php4.
http://forum.swsoft.com/pda/index.php/t-34613.html
502 - Web server received an invalid response while acting as a gateway or proxy server.
There is a problem with the page you are looking for, and it cannot be displayed. When the Web server (while acting as a gateway or proxy) contacted the upstream content server, it received an invalid response from the content server.
Something similar to the link below but I have no clue of how to change it on 8.6. According to the IIS settings of the webmail(horde)-site Horde is already using the Handler pointing to %pleskdir%\additional\php\php.exe, which is php4.
http://forum.swsoft.com/pda/index.php/t-34613.html