Customer support agent questioned if my email address format was correct - is '[email protected]' valid?

I just had the weirdest conversation with a customer service representative who seemed confused about my email address format. They kept asking me if I was absolutely certain that my email wasn’t something like ‘[email protected]’ with multiple dots and domain extensions.

This got me thinking - are there actually email formats like this that exist? I know Gmail supports plus addressing and dots in usernames, but what about having multiple domain-like structures in a single email address?

The whole situation was pretty funny because the rep seemed more confused than I was. Has anyone else encountered customer service people who don’t understand email address formats? I’m curious if there are legitimate email providers that use such complex addressing schemes or if this was just a case of someone not understanding how email addresses work.