Any know where to theme or brand or customise this page?
I have a customise cPanel theme and Nutsmail as my webmail. But why this page is not customised?
This page inherits the X3 branding/style that is set to the cPanel account this mail account belongs to. Therefore if you are logging in as firstname.lastname@example.org and the cPanel account for example.com is set to use the blackice style of X3 then the webmail interface will use the CSS etc. of the blackice style.