Although this isn't practical for everyone, this is one of the reasons I use a personal domain name and then host the MX record with an e-mail service.
That way if, for some reason, that e-mail service were to close my account, I could repoint the MX record elsewhere and still have access to my accounts.
That way if, for some reason, that e-mail service were to close my account, I could repoint the MX record elsewhere and still have access to my accounts.