Hi, does your client allow custom fields adding, forms customization and scripting like Outlook does ? Outlook is in fact customizable non-relational database of general small personal data “balls”. Is eM client just email client or does it offer similar universality like Outlook ? See Tools-Forms -Design Form in Outlook to display Form designer. Also, does eM provide categorization of not only emails but of all items in general ?
you can customize left and right pane and their subtabs in many ways or turn on/off specific folders. Regarding message part of layout you can change appearance of message list (turn on/off every possible column) and message preview part. And you can also theme eM Client or create the custom one.
But I am afraid eM Client doesn’t provide scripting and such universality (designing) as Outlook does.
Regarding categorization: you can indeed categorize all possible items (mails, events, tasks, contacts) by our application.