Back in '99 or so, there was a company called Halibut Stuff selling T-shirts at Defcon (and presumably other events) that included a free email redirect service with purchase of a shirt.

So I got a shirt that said "myself@iwenttodefcon7.andalligotwas.thislousyemailaddress.com"

Not too much later, I ended up working in software validation, and I broke so many login forms with that perfectly-valid address, I lost count.

Since then, Halibut Stuff dissolved and the forwarding service is long gone. If some HN reader wanted to set up a Mailinator-like service that generates absurd-yet-RFC-compliant email addresses for such testing, I think there might be a market.

Likely because of integration with legacy tech.

The 8-character limit was probably because the web site was just a fancy front-end to some decades-old mainframe system. You'd be surprised the age of technology and software big banks rely on. They tend not to fuck with a working system, partly because their reputation and millions or billions of dollars are on the line, but also because no manager wants to be the reason for a critical outage.