If you click the link I provided it takes you to the app on the google play store which also links to their website. It’s registered to Lavabit LLC. Additionally if you search for the app it is open source and attached to their GitHub account.

Was planning on hosting from my home server. Will definitely read up on those protocols and the recommendations. Have certificates and domain routed through cloudflare. ISP is optus but it’s not a business connection so that could be problematic r.e: spam filters :/

Sweet thanks. Only other thing I’ve been concerned about is opening ports into my network. Anything you’ve done to increase the security with this in mind?

By VPS I assume you mean I would need to spin up a new Ubuntu VM instead of say run it in docker along with a bunch of other services. Or are you saying I’d need to have a completely separate barebones machine?