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Always been there as far as I know.
Here's another thing, which might be the true purpose of this addon? With this addon active and enabled, logged out people cannot use the contact form. I get no link on my page and also get the "you must be logged in to do that" message when manually navigating to /misc/contact. THIS is the type of spam this addon is designed to stop.
Also stopping accounts like my test account I used and what you're describing, appears to be not a bug but out of the scope of the addon. Perhaps it can be added.
I really see no point in it, with this addon enabled legitimate people cannot contact the site. Might as well just de-permission the contact form for the entire "Unregistered/Unconfirmed" group. I really don't get the necessity of this.
If I have a legit user who cannot log in, I definitely want him to be able to contact me! With this addon enabled, he cannot.