Fair call. Other people have commented on issues with matrix so I won’t dilute the thread by repeating that. I mentioned session as an alternative because it meet the criteria set for the poster by being decentralised. It’s also E2EE and routes messages via onion so encourages anonymity.

There are a heap of comparisons available on the different encrypted messaging apps, but they all put different weight on various features which can skew perspectives. Here’s one for consideration:

https://www.securemessagingapps.com/

Personally I use signal, matrix and session, and think they all satisfy the requirements for my threat model.

Matrix has other issues, something like session might be more equivalent to signal.

If it’s Australian, don’t expect strong privacy. But then again, I wouldn’t expect that from a US based email provider either.

Source: am Australian.