@firstname.lastname@example.org I have to say that as much as I dislike them from a privacy and open source point of view (one gigantic commit every few months and versions for the android app), I have to say that they have the most user friendly, good looking, responsive and native cross-plattform clients of any messenger I know of.
And it's the only non-whatsapp messanger which is used by people I know.
Local network effects in messengers are fascinating. Here in Austria nearly everyone uses Whatsapp. Telegram isn't that popular, but used by many people I know. But interestingly hardly anyone use Facebook Messenger.
Mastodon ist ein soziales Netzwerk. Es basiert auf offenen Web-Protokollen und freier, quelloffener Software. Es ist dezentral (so wie E-Mail!).