Without questioning this line of thought, it seems like deduplicating by lowercasing and perhaps removing dots is a good choice, but stripping +suffixes seems l

Without questioning this line of thought, it seems like deduplicating by lowercasing and perhaps removing dots is a good choice, but stripping +suffixes seems likely to generate more user annoyance than it prevents. If I filter based on those suffixes and you send me mail and strip the suffix, I'm going to be pissed.