Hi Dan,
Thank you for your reply.
i think my description of the issue was not clear enough.
I want to add those people to a program (you are right campaign was the wrong word here) that added their email address on the paper registration.
Customer service enters this data manually into a marketo form on a landing page.
For new leads there is no issue. The problem I am facing is that we may alreay have a lead record of the person in the system with their email address. In case we receive a paper registration from that person without an email address on the paper, marketo will update the lead records. This is completely fine. However, I would not want to add this person to the marketo program because there was no Email address stated on the paper registration.
This is why i am looking for a trigger that is based on a field fillout.