Except there is no "the real world implementation". There only are lots of implementations that are incompatible with the spec as well as amongst each other. Inventing yet another variant of your own that also isn't going to be compatible with anything is not going to help anyone. Deviating from the formal spec because everyone practically agrees how to do things, albeit differently than in the formal spec, is something quite different from making shit up, and actually tends to be even harder than building things to spec, as there tends to be no easy reference to look things up in, but instead you might have to look into the guts of existing implementations and talk to people who have built them to figure out what to do - and you would normally start with an implementation according to spec anyhow, and only add special cases for non-normative conventions lateron.

Also, what exactly is the problem with email addresses? There is a very unambiguous grammar of those in the RFC, and there are lots of implementations of exactly what the spec specifies. Just because some web kiddies have made up some shit about email addresses and use that for validation, doesn't mean that postfix, qmail, or exim are written by morons.