How likely is it that you are sent to jail for 20 years and still care about your emails? If so, download them all and store in durable media.
Or just get sold to google/facebbok or a brilliant genius that have new grow hacking ideas.
PS: Yahoo! emptied my email twice. It is an old account from the times Yahoo! was the biggest thing in the Internet, that I'm not using regularly. So cross them out.
Best and most expensive. You'd probably need to make a contract with a third party to actively manage this for you. Ideally with your own domain to be able to switch providers. There are existing providers that do this type of thing: I have to do something similar with medical records retention and my retirement within a medical corporation in case I get hit by a bus tomorrow, but your timeframe is longer.
Cheapest. Practically if it's fairly hands off and reactive to cancellations or service outages you have a backup on another provider through forwarding or IMAP.
Middle ground? Business contact with Microsoft or a similar player. I'm not sure it's worth their time.
Be sure to set up limited power of attorney with your lawyers so they can manage your email account. Set up forwarding to route emails to them as you won't have access to a computer or phone. If a prison had a shared terminal then the warden and staff would have access to your emails. Probably best to keep that between you and your lawyers. And/or set up email rules to forward emails with specific subjects to your lawyers. It would also be important to discuss all of this with the lawyers that would be involved in discussions with the sentencing judge so that for example the lawyers may be able to visit you with a laptop that has offline copies of emails as cell service may be blocked. Expect this to ultimately be paper hard copies.
As for specific companies it is probably best to research the founders, board members, financials and company history of several providers. It's hard to predict which tech companies will still be around in twenty years. Even golden children like Amazon could be replaced by a new golden child but that is a much bigger topic.
That's a bit much, no?
> 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.