Certified email would solve this, if it was possible to self host it.

Unfortunately running it requires government approval and the resulting emails are legally binding, so I assume hosts will have to go through all kinds of security controls and audits.

This post glows so hard I’m going to need a pair of sunglasses.

It is possible to use Discord from the browser without necessarily making an account, but many big servers have restrictive measures that prevent users without a verified email addreds (or even a verified phone number, in the strictest of cases) to access. This will depend on your friends’ setup.

I don’t know if it’s possible to bridge Discord to Matrix, but I can tell you that it’s got a pretty prolific API for building bots and integrations, so someone might have already built something of that kind. Alternative clients are tecnically against the TOS (afaik) but I know of people who have built large projects without ever getting any complaints from the company.