The nice thing about email is that you can email someone with a gmail.com address from an outlook.com address. So you are not locked into gmail or outlook or amazon or ... any email service supplier. Very different from WhatsApp, Facebook, Instagram. LinkedIn and so on. You are locked in into these apps and are only able to communicate with other app users. You can not chat with someone outside these closed environments. The ability to communicate from service to service is called federation. My advice to you all is to use only federating services. That way we keep the market open and prevent creepy monopolists from getting too much control over us.