We apologize for any inconvenience that this has caused you. We appreciate your feedback on this matter and we are happy to submit this information to the appropriate teams. Below I have included a response that was made by one of our moderators when this thread was started, it contains more detail about how the sign-up process works. I hope that this helps.
The Constant Contact sign-up form has a built-in captcha that activates if a sign-up form receives more than 50 sign ups in a day. We are tracking feedback on having the ability to turn it on for every potential sign-up. I will make sure to note your interest in this feature within your account so our developers will see it.
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