The Quick Check view includes held messages that were caught by conditions other than our 3 most accurate conditions. The conditions which are excluded are SpamCop, Abuseat and Spamhaus. Our system statistics show that not only do those conditions catch the largest percentage of spam, they are also among the most accurate.
By removing them from the Quick Check view, we hope we can pare down your list, to eliminate the ones least likely to be legitimate mail. While many of the remaining filters are still very accurate, eliminating those most accurate ones can remove as many as 50% of the messages you would otherwise find in your Held Messages view.