In my organisation organisational change is mostly communicated through large meeting with all teams which are involved. The leaders of the change then present the change initiative with slides and open up the two communication channel in the meeting to answer questions. The other communication channels are internal groups where the change is announced and members can give feedback. In my organisation it seems to work best when the change is communicated in large meetings and then followed up by an email explaining the change again to all members of the organisation.
