Sizing a First Drop to a Directory's List

A directory's list tells a mailer what a business is and where it sits in the trade, not who inside it signs the check. A first drop to those names can measure deliverability, reply rate and cost per reply against a control cell. It cannot measure lifetime value, because one mailing produces one reading and no purchase history.

The aviation trade has carried directories for decades. One archived example, the portal once run under the name ProAero Business, listed airlines, airports, FBOs, repair stations, flight schools and parts suppliers across several regions, and its captured pages show how wide a generalist directory gets. That width is the point and the problem for a mailer.

What does a directory actually know about the businesses it lists?

A directory knows the trade category, the location and the public contact channel. On the archived pages of the aviation portal cited above, a listing carried a company name, a city and a country, sometimes a phone number and an e-mail role such as sales or customer support. The operator behind that portal described itself as a professional aeronautics business corporation established in 1999, with a stated head office in Tampa, Florida and offices announced in the United States, Puerto Rico, Italy and Brazil.

That is a firmographic record. It is not a buyer record. The directory does not know the size of the operation, the fleet, the annual spend on the category being sold, or the name of the person who approves a purchase. A mailer who treats a directory as a list of decision makers is guessing. A mailer who treats it as a list of qualified trade addresses is on firmer ground.

What a first drop can measure

A first drop to a directory's names answers four questions and no more.

• Deliverability. How many pieces reach a human or a mailbox, and how many come back undeliverable. This is the cheapest reading and the one that decides whether the list is worth a second look.
• Reply rate by segment. Split the file by trade category, by region or by listing depth, and the reply rate per cell shows which slice of the directory behaves.
• Cost per reply. Total drop cost divided by replies. This is the number that goes next to the response rate on the test sheet.
• Cost per booking, if the reply channel is staffed to close. A reply that never reaches a phone line or a booking desk is a reply, not a sale.

Announce the protocol before the results. One list, one mailer, one offer, one expiry date, one reply channel, and a control cell held back from the drop. Without the control, the mailer cannot separate the list from the season.

What a first drop cannot measure

A first drop cannot measure lifetime value. One mailing produces one reading. A directory name that does not reply in March may reply in October, and a single drop has no way to see that.

It cannot measure the quality of the offer. If the offer is weak, the list looks weak. The two are tangled in the same reply rate, and only a second drop with a changed offer separates them.

It cannot measure the whole directory. A generalist file covers airline and airport directories, FBO and MRO listings, air charter, fuel, parts, avionics, aircraft sales, maintenance, flight training, aeromedical, helicopter, glider, skydiving, dispatcher and ATC training, jobs, military aviation, insurance, finance and regional sections. A first drop to the full file is a sample of a sample. The mailer who wants a reading on one trade category should pull that category as its own cell.

How should the first drop be sized?

Size the first drop to the smallest number that still produces a readable reply rate, and no larger. If the expected reply rate is one percent, a cell of one thousand names returns about ten replies. Ten replies is a direction, not a verdict. A cell of five thousand names returns about fifty, which is enough to compare two cells against each other.

Cost drives the ceiling. At a known cost per piece, the drop size times the piece cost is the cash at risk before any booking. The break-even is that cash divided by the contribution per booking. If the break-even sits above the number of bookings the file can plausibly return, the drop is too large, not too small.

Hold one cell back. The control cell costs nothing to mail and is the only clean comparison the mailer will have.

Which names should be pulled first?

Pull the names whose trade category matches the offer. A directory that lists flight schools, maintenance facilities and parts suppliers in the same file is three lists wearing one cover. A mailer selling avionics work pulls the maintenance and avionics slices. A mailer selling a training package pulls the schools and the career changers.

Then pull by region. A directory with regional sections for Africa, Asia, Europe, North and South America and the Middle East is a set of separate postal realities. Postage, delivery time and reply lag differ by region, and a single blended reply rate hides all of it.

Then pull by listing depth. A name with a phone number, an e-mail role and a street address is worth more than a name with a city and a country. The deeper the record, the higher the piece cost the mailer can justify.

What the record says about the source file

The archived aviation portal is a useful reminder of what a directory is. Its captured navigation was wide and its interior pages were often empty shells, and for most of its life the site announced a work in progress. A mailer who buys or rents a file built from a directory of that kind is buying coverage, not depth. The record shows the categories and the regions. It does not show the buyer.

That is the whole discipline of a first drop. The directory supplies the trade addresses. The mailer supplies the offer, the protocol and the control. The reply rate that comes back belongs to the campaign, not to the list, and the test sheet should say so.

Sources

The Federal Trade Commission's guidance on mail, telephone and online sales, and the United States Postal Service's address quality standards, set the rules a first drop has to follow. The archived captures of the aviation portal cited above were read from the Internet Archive's CDX index.