Hide inactive users from mail-/customer-selection

Right now every user gets displayed in every selection and there’s AFAIK no way to prevent this (except deleting the user).

Yes, they’re visually crossed out but that’s still kinda meh for two reasons:

  1. it needlessly blows up the UI at some point
  2. some agents seem to have the ability to completely ignore the difference in appearance and still message inactive users (which in our case - is bad)

There probably are use-cases where it’s useful to see inactive users so an option in the admin area to toggle the behaviour probably would satisfy all.

For the sake of completion, my quick&dirty mockup: