[mountainriver]

What are some good alternatives?

[1MachineElf]

None for email, unless you roll your own[0][1][2][3][4].

[0] https://github.com/foxcpp/maddy

[1] https://github.com/LukeSmithxyz/emailwiz

[2] https://github.com/iredmail/iRedMail

[3] https://github.com/Mailu/Mailu

[4] https://github.com/docker-mailserver/docker-mailserver

[peakaboo]

https://fediverse.party/

Peer to peer services with encrypted communications are impossible to centrally control and monitor.

[0xdeadb00f]

AFAIK none of those are "encrypted" outside of TLS and disk encryption (that is, if your instance uses encryption at rest, which it might not).

Regardless, they are not suitable replacements for email.

[dewey]

Don't do things that get you into trouble over email or use Tor / VPN.