Is there a way to run a report that will show me all of my leads who have opened ALL of our mailings? I am not looking for leads who have opened a mailing or 2, but leads who have opened every single email that we have sent.
Probably creating a smart list with a filter "Opened Email" and specific "Email Is" - click the green plus sign, and then "Select All". Delete the filter that's defaulted there "Date of Activity". See if that gives you the list you're hoping for.
Actually what Rebekah suggests will bring up leads who opened at least ONE of the emails listed. That plus sign is OR.
if you wanted a list of leads who Opened all of your emails, you would need a lot of filters that said Email IS X and Email is Y..,..
I suspect you have sent a lot of emails, so this seems like an unnecessary list pull given that Opened is unreliable.