Legitimate Users Denied Registration

Hey. I have built a custom website and have integrated the CT API into my registration so it checks the users email before allowing users to register. I’ve been having some people help me beta test and I’m getting reports that the API is blocking a lot of their registration requests.

I’d like to make sure this isn’t an issue with my code or the information I’m sending to CT. (Like, am I accidentally sending incorrect time or something else.) Or if these legitimate emails have just been blacklisted for one reason or another.

I know this question is pretty generic, I can provide details, but I wasn’t sure if this was the right place to ask about the API.