I have my own domain. I've been asked for my email, to which I replied "myname@foo.example" and they replied "myname@foo.example.com?".
edit: Changed domain based on ButlerianJihad's suggestion
edit: Changed domain based on ButlerianJihad's suggestion
https://en.wikipedia.org/wiki/.example
A real domain, for all your fake purposes!
"Do you mean 'myname@foo.example.com'?"