Webmail is showing a White page

[manoochehr]

Hi Experts

I have problem with plesk webmail.
Plesk Webmail is showing a white page when I open it from an address like 'webmail.persiclub.com' or 'webmail.persitools.ir' using Firefox

and showing "the page can not be displayed" when I open it using Internet Explorer

but when I open it from IIS manager, it's working fine.

So what is the problem? It's urgent for me