One simple thing you could try is to just check for the
Eventually, we expect spam bots to grow smarter, and be able to pass a false checksum along with their submissions. Once this starts happening, we’ll want to really Certify that a verification that’s been submitted to your back-end really was verified. This is where you would use Certification.
In conclusion, if you want to be really sure that any email address that is submitted to your form is guaranteed to have been verified by goodforms.com, then you’ll want to Certify the verification when it’s submitted.