In the end, we need to trust someone. But we dont read their minds:). And it could be, after all, a big fall.
No, you don't need to trust anyone, and should not. That model's long been broken. You should audit the code, spec and docs and then trust that.
We"ve got pgp. Thanks God.
And have only thus secured the message body. A valuable tech advance to be sure. But far from approaching a near wishfully complete checklist solution.
But a 100% reliable and bulletproof email provider? No.
Countless businesses fail, sellout, etc every day and that will not change. It is proven since dawn of business for them to fail or at least morph into something unrecognizable. [Note it doesn't take $much/account to run a good barebones email service 100%, especially if you stick to only mail and cut features. There's no reason we shouldn't have 50 punkish ones in curious jurisdictions to choose from by now.] Back to p2p... your recipient, and your peers are all independent businesses. Look out in your city, other than you and Alice who both are 'up' by definition of wanting to talk some method, you could fail many people/nodes/businesses and still route a p2p message through. It's hard to eval trust of a single business or %'s of nodes. Yet just like all the millions of torrenters, your odds of the majority of the nodes [which have real IP's hard to fake in the disparate millions] being on your side are probably better with p2p than whether one single brick and mortar business is screwing you over, or forced to to so. Business centralization, vanity, monetization, etc to run the lava*'s, proton's and so on is counter to some of the problems they attempt to solve. Their real benefit is often adding research to the educational pile of debunked non-solutions to such problems. A natural selection process of sorts. And as legal test cases for fighting the good fight, pushing boundaries and changing that end of things. If Ladar didn't stand up and speak out we wouldn't know to evolve those parts of our process. We need more people like that.