There is a way to get this information in a couple of different ways, it just depends on what specific information you are looking for.
If you are looking for a list of all of the people who are registered who are also contacts that you have permission to email, you can upload a list of your registrants to a new list in your account. Any contacts that did not give permission will not be added to the list.
If you are looking to get a list of the contacts that checked off the box, you can see the new people that were added to your list by adding your registrants to a list, and then searching by Date Added (either within your account or through an export). You will see the Source as Event if they signed up from a registration form. If you want to manipulate the data more you can export it out to filter by more than one column.
Please note, the contacts that are set as "No Permission Set" can be viewed by Source. If this source says Event, then they registered for you event, but did not check off to join the list. These contacts will receive event communications, but will not get other emails sent outside of the specific event that they registered for.
Please let us know if you need any help in finding this information, we would just need to know which event you need us to take a look at.
Thank you so much for the reply Samantha_O! Unfortunately, I still think this will not work for us because of the way the event was initially set up. The person setting up the event set it to add people to our "Dynamic" list if they checked the box. Unfortunately, our "Dynamic" list is cleared every night by an external database program--meaning that the people's emails stay in Constant Contact, but everyone is removed from that list. So people who checked the box were added to just that one list, but then removed from that list the night after they joined...which (correct me if I'm wrong) then makes it looks like they have no permissions set still...correct? I'm going to try, but I'm thinking we are out of luck.
If the contact is deleted their permission status should not change. The contacts in "No Permission Set" should only be contacts who registered but chose not to join the mailing list.
Let us know if you need help with getting the lists recreated.
If I send an event invitation to someone who is already on one of our email lists, and they don't check the box to opt into to a list, do they get removed from the list? Say they're already on a public outreach list, but I've uploaded a spreadsheet with their email address into an event registration. If they don't check the box to be on the public outreach list, are they removed from it, or are they left on it because they were already on that list in the first place?
That is correct. If a contact already exists in your Constant Contact database and they leave the check box empty while registering for the event it will not remove them from the list they are already on.