Hi! I want to start by mentioning that there isn't a quick and easy way to get this list, mainly because we don't recommend sending to folks that didn't open. Many servers look to see if you're sending the same email to the same address multiple times, and it often results in being blocked by that server. There is also often a legitimate reason for folks not opening, and we'd hate for you to possibly become a bother to anyone in your audience with multiple sends. However, if you want to find these, there is a way! Here are the steps:
1. Go to your response section, click on your opens, and click to "save as a search." That list of opens will now be saved as their own search.
2. Go to your main audience page, and create a new group called "opens" (or something similar that will let you know who these folks are).
3. Next, click on the searches tab (it's near the spot where you can create a new group name). Open that new search you made containing the list of people who opened your mailing. At the top of the list of names, select to take "all" members of the search, and "copy" them. Select "copy to groups" and copy them to the new group you just created.
4. After those are copied, head back to the searches tab under your audience section. Click the button at the right that says, "Create a new search." Build a search that finds people that are "in" the groups that you originally sent your mailing to, but are "not in" the "opens" group you just created.
That will give you a list of the folks who didn't open the email. I hope that helps, and let us know if you have any questions.