Me and some colleagues are not happy with some events in our company. We'd like to prepare a whitepaper (maybe not the correct term) for the management so that they become aware about the things that go wrong.
While we prepare that, we would like to keep it secret, so we avoid Email, Skype etc. which are potentially under control of our employer. Therefore I'm looking for a tool that we can use for communication and that supports plausible deniability.
A chat-like program would be ideal, but an Email-like program would certainly do as well.
Such a tool would need to work on Windows 10, be gratis, ideally be portable and work offline (as far as possible; it should definitely not be a website; of course message exchange might use Internet routing).