I am not super excited about this, but it is a nice addition. Maybe you want to add an option upon deactivation, which allowes the user to decide when the inbox will be activated again? This could offer something like
automatically enable inbox again after <x> days,
automatically enable inbox again at <date>, and
never (inbox needs to be enabled manually)".
Without that it might happen that someone forgets about the deactivation and just never enables the inbox again. It is also nice that one does not have to care about activation later, because usually you know when you are back (e.g. from a vacation) and want to participate again.
