Not 100% what you want but the closest I know of is hey.com (I'm not a customer yet but I am evaluating them). As far as proof that they will, who knows, but so

Not 100% what you want but the closest I know of is hey.com (I'm not a customer yet but I am evaluating them). As far as proof that they will, who knows, but so far they've kept this kind of promise for their other products over the past 2 decades... > If I cancel, can I forward my @hey.com address elsewhere? Yes. As long as you’ve paid for your first year of service, you can forward any email you receive while your account is open, or after it’s closed, to any other email address you’d like. Trial accounts don’t include forever-forwarding either. > If I cancel, does someone else get my @hey.com address? It depends. As long as you’ve paid for your first year of service, your @hey.com address is yours forever, even if you stop using HEY and don’t pay for HEY in subsequent years. That means no one else will ever be able to claim your email address, or receive password or security resets at your original @hey.com address. If you don’t pay for your first year, or you cancel and request a refund within the first year, or you never go beyond the free trial, your @hey.com email address will be recycled after 90 days and made available to someone else. https://www.hey.com/faqs/ https://www.hey.com/faqs/