A friend of mine had an email address of the format "username."@example.com which AFAICS is legal (as long as you keep the quotes around the username and th

A friend of mine had an email address of the format "username."@example.com which AFAICS is legal (as long as you keep the quotes around the username and the trailing dot there). But damn if it didn't break a lot of systems out there! In the end, he got booted off his email provider as they were upgrading their mail systems -- to one that didn't support accounts named with a trailing dot!