I recently submitted a request to stop fake emails being accepted into my CC mailing list after Captcha is ineffective in Wordpress plugin.
I don’t think it is a good idea to send a confirmation opt in email to someone who is trying to hack into my site by privileges granted after joining a Constant Contact email list. Seriously, how does asking them to confirm the bogus email stop them from then confirming the bogus email and thereafter becoming a website exclusive member?
This is quite a serious flaw in your processes in CC management and needs a solid rethink.
You should have the ability to blacklist requests to join a CC email list using wildcards once an email address is known to be suspicious or obvious fake.
If I get ten requests in a day from a domain using different first names I don’t want that email address to be sent any correspondence or opt in requests nor do I want them in my list.