> broke so many things I've been doing it for about 20 years, and I can't even recall anything being broken or not working, but maybe I'm not using services th

> broke so many things I've been doing it for about 20 years, and I can't even recall anything being broken or not working, but maybe I'm not using services that connect like that. The most annoying thing I can think of is when I sign up using "example.com@my.domain" and it tells me "example.com" isn't allowed in the email address... but this is rare, and easily worked-around. On the other hand I know several services that were either compromised or sold their email list. Back when email filtering was mediocre at best, it was easy to make rules to completely filter those addresses out.