My ISP went under - how do I recover mail email and email address?

First let me address your question directly: if your ISP has truly disappeared, then to the best of my knowledge there's no way to retrieve the information from them, and there's no way to use or redirect the email address you may have had with them. The best you can hope for is that some other ISP will swoop in to save the day and take over your old ISPs assets and make them available to you. It's certainly not anything that I would count on.

While ISPs going under is an infrequent occurrence, the scenario is very similar to one I see often: losing your free email account. In both cases everything you have is gone, with little-to-no chance of recovery.

And from the free email scenario we can also learn the steps you should take next time to prevent the extreme data loss you've just experienced.

Select a good provider. This is difficult, since some of the best ISP opportunities are with regional providers as opposed to some of the huge heavy hitters and/or telephone companies. Personally I've had a great relationship for many years with a local western-Washington ISP, Avvanta; they've provided my wife's business with connectivity for nearly 14 years now. The problem, of course, is that it's the smaller ISPs that are perhaps the riskiest. The chances of, for example, your telephone company going away any time soon are pretty small. Unfortunately there's a cost there as well ... I stopped using my telephone company as my ISP because their customer service was absolutely abysmal.

But like I said, ISPs disappearing is something that happens very infrequently no matter what the size. Ask around and see who people in your area are using and how satisfied they are.

Backup your email. Webmail is really, really convenient, but as you've seen it places all of your eggs in one basket. If that basket goes away then you're in big trouble.

My recommendation is that you use an email program that you run on your own PC to download your email via POP3, and then back that up as you back up your PC. You can continue to use webmail, but if the service suddenly disappears you at least have your backups to revert to.

Alternately, what I see many people doing, is configuring their primary email to automatically forward a copy of all incoming email to another service, often a free service such as GMail. This can be a good solution as well, if your provider supports automatic forwarding.

Important: note that neither of these solutions support backing up your address book that you may accumulate using web mail. You should still export your address book from your web service to your PC and back it up periodically.

Consider getting your own domain name. When your ISP goes under you've lost not only your mail, but your email address. Presumably people trying to reach you through that address will get bounces, or nothing at all. There's typically no automated way to get email sent to that address forwarded to another. Forwarding services require the cooperation of the service hosting the "old" address - in this case that's your old ISP, and they're gone.

Registering and owning your own domain frees you from any ties to a specific ISP. For example, let's say I own the domain "example.com". Using only the domain registrar I can make any email address on that domain. I might make one called "leo" at example.com, which I tell everyone to use. I then have the domain registrar automatically forward email sent to that address to my "real" email account with my ISP or even a free email service. People can continue to email me at that example.com address, regardless of whether my ISP goes under, or whether I lose the free email account that it points to. If there's a problem, I simply change where the example.com email address is forwarded and no one's the wiser.