If you want to move your email from a big hosting provider to your own self-hosted email service (or to any other 3rd-party-hosted email), make sure that a) you're using IMAP, and b) use one of the many #FOSS tools (there're lots of proprietary options, but from what I've seen, they're not a lot better and can cost heaps) to do an IMAP level transfer from your old service to your new one. And you need to c) do this *proactively*, because it ain't happening if access to the old service is gone.