In the current version, it is possible to customize the color of the interface and display of the left main menu at the message list page.
 
To change the appearance, click Options at the top menu.
If there is no such item in the menu (usually at lower resolution monitors or because of small size of the browser window), click the Other tab.


At Options page select General Settings.
  • Use the item Look and Feel to change the color
  • To save the horizontal space by hiding icon's names in the left menu select an option Default view in the  Menu presentation
Confirm the settings by clicking on the button  OK
 

Note 1: Additional color customization is not currently available (it is planned for future versions)
Note 2: The change of appearance is not available for email variants without BUSINESS Mail