Issue #2936032 by gambry, nlisgo, alexpott, cwells, cilefen, Darvanen, DamienGR: Sites named with special characters cannot send mail

Issue #2954825 by rakesh.gectcr, tresti88, gnuget, borisson_, DamienGR, Prashant.c, amietpatial, alexpott, joachim, Berdir: Update the user.api.php documentation and add the correct type hints in the user's hooks implementations