Other alternatives: Status(https://status.app), speek!(https://speek.network), Briar(https://briarproject.org), Cwtch(https://cwtch.im) and Tox(https://tox.chat/index.html).
Obsidian and logseq
You should use it. Strong E2EE and fully open source(unlike mega). Also bult-in notes and chats. 👍
Or if you have a lot of money - StartMail. It has unlimited aliasing feature and UI is very good.
Maybe kMail(very beautiful) or disroot(more about freedom and not very beautiful). Both open source.
StartMail, Soverin, Disroot, Infomaniak Kmail, Mailfence, Mailbox.org, Kolab Now And Posteo
Use any matrix client unstead.
Other alternatives: Status(https://status.app), speek!(https://speek.network), Briar(https://briarproject.org), Cwtch(https://cwtch.im) and Tox(https://tox.chat/index.html).