I've got a first@last.family. My dentist and several large companies refuse to accept this as a valid email address, so I have to use an email that doesn't identify me personally by name (uses efreak instead of my name). This annoys me every time I deal with them, especially since some of these sites use my email address as a username. I've been locked out from logging in on other devices a couple times for trying too many passwords when the problem was the address, not the password.

Interesting, so maybe I should have used a different prefix. Weird design.