For my directory I require submitted websites to be registered via e-mail, basically I send an e-mail with a registration link for them to click on. I would say that 30% haven't clicked on the e-mail registration link, after they add their site a web page comes up and tells them that they should expect an e-mail and they have to click on the link. Is 30% high? What's your experience with submitted websites not being registered?
Clicking on email buttons is not something that a lot of folks do because most like me I think believe that in many instances email back in is trouble, obviously not all, you just open up a can of spam I am sure this is not the case with your system
Yes few directories require the user to click registeration link in their email box, and finally they got human submission, it seems good technique to avoid automated (robot) submissions. But, i think most of users who are submitting sites in bulk, they avoid to visit their inbox in order to complete the registeration process.