They can bypass it, and as the user you can also use any other sign or character that you want. If you email is foo@ then you can use the letter x, as registrat

They can bypass it, and as the user you can also use any other sign or character that you want. If you email is foo@ then you can use the letter x, as registrationxfoo@. A popular choice for a company email is first.lastname@, so you can use a . for it, or the - character. + is just what some program, like procmail and Sieve, will recognize without much trouble. Using a a catch-all email with your own domain works also perfectly fine. Doesn't work as well if there is multiple email users of that domain.