People have a problem with Signal: you cannot self-host its server. Sounds like you want to keep the mobile client, swapping out the server underneath. I think

People have a problem with Signal: you cannot self-host its server. Sounds like you want to keep the mobile client, swapping out the server underneath. I think you’re better off waiting until Moxie allows setting the remote server, and wrapping the Signal server with the email options you want.