From a code standpoint it doesn't look too bad, but from a logical standpoint you have a lot of issues. First you exclude a whole lot of valid email addresses by making assumptions about what characters are allowed in an email address (pretty much anything is allowed on the left side of the @). You have also made some big assumptions about characters that will not appear in your customers names, unless you don't want any customers named O'Hara or O'Malley. From a purely nit-picky point of view, the reserved-username message will probably lead people to believe their username must be a non-dictionary word.