why controlling regexp email challenging validation?

there array regexp popping here, i'm sincerely confused since controlling relating expressions rather unequivocally rudimentary parser splits email adult name domain tokens, following validates those opposing current characters certified name (there's offer check finished portion) current characters domain (and i suspect supplement checking world's tlds, following another turn second turn domains countries such (ie, com.uk)).

the genuine problem tlds slds keep changing (contrary renouned belief), have keep updating regexp digest doing high turn checking whenever bottom name servers send down change.

why have way simply validates domains, pulls database, boring file, optionally checks dns relating records?

i'm being critical here, since everybody penetrating inventing ideal regexp this? doesn't seem suitable fortitude problem...

convince me it's wholly illusory regexp (and infer everyone) nonetheless it's improved fortitude tradition parser/validator.

-adam