User folders sorted by department or server group

I got asked by a colleague if it is possible to sort the Users because he had about 60+ Users in the Direct Messages section.

It would be nice if you can sort it by a specified department (or Position) or that you can create User groups (with specific permissions for example) and that they get sorted in categories like this.

An other way could be that everyone can create custom folders with users in it and can expand it if needed.