Login: Let end users know if they have no account with that email address.

Hi there, lots of our end users have the following issue:

If a user clicks on “reset password”, they will be told that “we emailed you password reset instructions” even if they inserted an email that is not registered. 
Instead, I would expect the message: “you are not registered to this community with this email address.”

Why does it matter?

We have 2 separate communities that look almost exactly the same (different language). On a daily basis, users will try to log in to the “wrong” community to which they have no account to. They login fails, and the error message says “wrong email and/or password”. So they assume their password is wrong, because they obviously think they are registered (but they are registered in the other community).

So they click on “forgot password”, enter their email, and get the following message

But that’s a lie, because they did not get any reset instructions; they got no email at all.

So then they try again and again and end up frustrated.

So they write us an email trying to get help, (which we have to answer every time), or even worse, they give up and stop trying to use the community altogether.

Instead, it would be good if they were told the truth: that they are not registered to this community.