Taking all the documents that aren't in the Sent view isn't quite right, because there are a few documents that aren't in the Sent view that are also excluded from the All Documents view. The logic you want is:
SELECT (in the All Documents view) AND NOT (in the Sent view)
So, first make a copy of All Documents. You're going to keep the selection formula from the All Documents view, and put & !( ) after it, like this:
SELECT ( @IsNotMember("A"; ExcludeFromView) & IsMailStationery != 1 & Form != "Group" & Form != "Person" ) & !( )
Now, just copy the selection formula from the Sent view and put it between those empty parens, so the result is this:
SELECT ( @IsNotMember("A"; ExcludeFromView) & IsMailStationery != 1 & Form != "Group" & Form != "Person" ) & !( DeliveredDate = "" & PostedDate != "" & !(@IsMember("S"; ExcludeFromView)) )