You can try Delta Chat. It's self hosted, E2EE and they use SMTP and IMAP protocols, so it's compatible with any email account (not 100% real this, didn't work with tutamail or Proton mail)
You can try Delta Chat. It's self hosted, E2EE and they use SMTP and IMAP protocols, so it's compatible with any email account (not 100% real this, didn't work with tutamail or Proton mail)