I don't know COBOL, but I do like this joke (which has been floating around much longer than this Reddit post): https://ancillary-proxy.atarimworker.io?url=https%3A%2F%2Fwww.reddit.com%2Fr%2FProgr...

mairix is another good solution for searching them, once you've got them in local mbox/mh/maildir spools. I think back when I was converting to maildir I scripted mutt to copy them in, but it's obviously harder if you've got them in proprietary formats.

I'd guess the reliability is somewhat higher than trusting your data to a single hard drive. You can back up to DVD or another drive, but that's a pain in the butt, and still doesn't help you if your house burns down.

I get a fair amount of "legitimate" spam to an email address which I only ever had in the InterNIC database. So, there's at least one company tying addresses to emails based on domain name contacts.