We begin by turning a requirement into filters that return a number. Categories are checked against the underlying description, not the label attached upstream. Anything that could not be filled is stated plainly rather than padded.
Catch-all detection
Separating addresses that are confirmed from addresses on a domain that accepts anything.
Seed insertion
Placing known addresses in the file so you can see for yourself what was sent and when.
Franchise handling
Separating independently owned sites from company-owned ones where the evidence allows.
A short brief is enough to start; detail can follow once the size is known.