I was wondering if anyone knew the standard system Smart List for Possible Duplicates? Ours has been edited from the original, and I'm not sure what it was. Currently, I just have "duplicate fields" on email address, but I seem to recall there being more.
Email address is the only criteria in that smart list out of the box. You remembered it correctly.
Email address is the primary criteria for the Possible Duplicate system smart list. But, you can also use custom logic to find the possible duplicates.