An email address is the key to almost every other account you have. If it belongs to a provider, so — in a sense — do all of those accounts.
Why a domain changes everything
With an address on your own domain, the mailbox provider becomes replaceable. Unhappy with the service? Point the domain at a new one, move your archive, and nobody you correspond with notices anything.
- Register a short, boring domain you are happy to keep for life.
- Turn on auto-renewal and set a calendar reminder anyway.
- Use a provider that supports custom domains and standard IMAP.
- Keep a local copy of your mail archive.