Two lines to make sure there are no invalid email addresses in the returned result of a propel query. To use in Symfony... The expression ensures that the string starts with at least one character which is not @, then a @, then another non-@ non-empty sequence, then a dot, then at least two non-@ characters (ie. TLD) and end of string. I.e. not RFC822 conformant, but most of the time sufficient.
$regex = UserPeer::EMAIL . " REGEXP '^[^@]+@[^@]+\.[^@]{2,}$'";
$criteria->add(UserPeer::EMAIL, $regex, Criteria::CUSTOM);