A counter argument on this is also to hold a standard across your software suite. The amount of times i have found websites that allow `email+tag@example.com` o

A counter argument on this is also to hold a standard across your software suite. The amount of times i have found websites that allow `email+tag@example.com` on sign up but then promptly break at the backend has become more than i can count on one hand. While the argument that supporting all valid email addressing may not be the best idea, holding a uniform standard across your own systems is.