That does mean that there will only be an ad-hoc undocumented standard for email addresses, rather than one that's serviceable. Web application validation form

That does mean that there will only be an ad-hoc undocumented standard for email addresses, rather than one that's serviceable. Web application validation forms add a different layer to the standard and are sort of hard to tame; anyone can push together a few lines of PHP or Javascript code and conjure their own email address standard out of thin air.