<?php $email = "mail@domain.de"; if(preg_match("/^([a-zA-Z0-9]+([-_\.]?[a-zA-Z0-9])+@[a-zA-Z0-9] +([-_\.]?[a-zA-Z0-9])+\.[a-z]{2,4}){0,}$/", $email)) echo "Gültige E-Mail Adresse"; else echo "Ungültige E-Mail Adresse"; ?>