alt Hacker NewsThink about what you're saying: someone is near the top of the sales funnel and despite the odds you've convinced them to provide their email so you can start the process of trying to convert. Even if you are good you'll still lose 80% of people from this point before you see a single dollar. Now, inject some extra weird, sketchy-sounding friction AND ask them to change their email provider, something 99% of employees never think about let alone control. Not sure how old you are but you'd have better luck convincing users "this site works best in IE4".
Right, letting users frustrate silently, without explaining to them why they don't receive correspondence is the way to go. Discussing my age/gender/race isn't productive either. Dont rage, just pay attention to what's written. I only suggest them to select a different e-mail for better experience, not reqiring it. And the actual wording of this suggestion should always be developed in collaboration with company's layers and marketing teams.