I'm looking for a way to implement an extra field for a validation code.
Code is provided by us and we are sending a link to a hidden page with the autoreply.
So we need to make sure that only people who filled in the correct validation code receive this link.
Furthermore, we need to have several validation codes that work. So there need to be able to put in 10 or 20 validation codes for matching.
How do we do this?