We've lost the basic ability to store and process email. Back when we all used terminals connected to one big computer (Unix, etc.), it was clear where your mail lived: in specific files. You could access it from anywhere (via modem), and you could process it with tools (grep, sed, etc.), use "tar" to back it up, encrypt it with PGP, or basically do whatever you wanted with it, effortlessly. It was YOURS.
Nowadays, half your email lives on a remote IMAP server: accessible from anywhere, but inaccessible to your local tools, and if your mail provider ever gets shut down, you could lose it all. The other half lives in local mailboxes on your desktop or laptop, accessible only when you're physically next to the machine. Or worse, if you use two desktops (one at work, the other at home), you might have local mailboxes on each, making it impossible to do a full search of your email. Some people work around this by carrying a thumbdrive and putting all local mail folders on it... but then you have to back up the thumbdrive, etc.
This is why I download all email from my ISP to a Linux machine at home (via fetchmail), access it via OpenSSH, and read it in emacs, or run a local IMAP server. This provides all the benefits of the old "terminals" model. The downside is you have to be a computer wizard to set it up.