Why do you want to detect the difference between a user signing up with one email account twice or two different accounts? It's folly to try to detect this in this manner and you will only piss off regular users.

The service that's trying to strip the +'s are trying to prevent users from using their (usually free) service in a way that will cost them more money, but never convert to and profit.

i understand why they do it, but i can't condone it off course.

The service should just allow it, and make sure the appropriated subscribing fee.

> The service that's trying to strip the +'s are trying to prevent users from using their (usually free) service in a way that will cost them more money, but never convert to and profit.

I can always create multiple email accounts, you know. So I don't see how spending development efforts to parse and detect + and . is effective.

It's a pointless and stupid point.

It is extremely easy to setup extra email accounts, so preventing people from doing so with slightly less work is pointless.

It is stupid because it could prevent someone from using their real, valid email address because it matches another, different, valid email address.