That depends on what you’re trying to do. If you want it to be an obvious example, @example.com is great. If you want it to look like real data, such as in a demo or a screenshot, it’s not so great.
It’s a bit like saying that every demo user should be called John Doe or Jane Doe if they aren’t actual people.
It’s a bit like saying that every demo user should be called John Doe or Jane Doe if they aren’t actual people.