You shouldn't use you@company.com as your main email, you should have your own domain. So `something@yourdomain.com` will always be yours no matter if you self host or use 3rd party. I currently use Fastmail and i've been very happy with them. If they fail or turn evil, I'll switch to something else maintaining the same address. Emails themselves should be downloaded/backed-up regularly, kind of like important documents you'd have on your disk.