We are identifying them in both ways actually - people that clicked to our landing page from an email but didn't fill out the form as well as known leads who viewed the page but did not complete the form.
Thanks for the recommendation of scrubbing the list again those that did fill out the form, Michelle - great idea!
So now we are going to send follow up emails to those who abandoned, but I am looking for some guidance or suggestions on how soon after they abandon we should follow up as well as frequency of contacting them.