Unaddressed Mail in Australia: How It Works and How It Differs from Letterbox Drops

Unaddressed Mail puts catalogues, flyers, and other letterbox advertising into every letterbox in the suburbs or postcodes you choose, with no name or address on the item. It's delivered through Australia Post with the regular post, and you can book it directly with Australia Post or through a provider such as Oppizi that runs it alongside your other offline channels, so it's one of the simplest ways for an Australian brand to cover a suburb, a region, or the whole country without a mailing list.

It's also easy to confuse with a letterbox drop, which reaches the same letterbox by a completely different route. This guide covers how Unaddressed Mail works, how to book and track it, and when a Letterbox Drop is the better fit. Oppizi has distributed 76M+ pieces in Australia since 2014, so we've seen what each channel does well.

What is Unaddressed Mail in Australia?

Unaddressed Mail is a postal channel: whoever you book it with, Australia Post delivers your item to letterboxes alongside regular addressed mail, and the item carries no recipient name or address. That's what qualifies it. You can send to consumers, businesses, or both, in the suburbs or postcodes you pick, or nationwide. Australia Post can deliver Unaddressed Mail to up to 9.3 million letterboxes that accept advertising (as at June 2025).

It suits flat, flexible items, such as postcards, envelopes, catalogues, flyers, brochures, coupons, samples, and wrapped or folded pieces. The smallest booking Australia Post accepts is one suburb, postcode, delivery address type (such as PO Boxes), or postal round, and for a suburb or postcode booking it delivers to the best-fit postal rounds.

Unaddressed Mail isn't a catch-all name for anything that lands in a letterbox. It's the channel delivered through Australia Post, booked either directly with Australia Post or through a provider like Oppizi, which also runs Letterbox Drops, Hand-to-Hand Flyering, Addressed Mail, and Out of Home from the same platform. If you're weighing it against mail addressed to named customers, see our guide to direct mail vs Unaddressed Mail.

How does Unaddressed Mail work?

Whether you book directly or through Oppizi, the steps are the same: choose your areas, book a delivery week, print to Australia Post's size rules, and lodge the printed items. With Oppizi, our team handles the booking, printing, and lodgement for you. Australia Post then delivers them Monday to Friday of the week you booked, excluding public holidays.

1. Plan your areas. Campaign Targeter, Australia Post's free planning tool, maps coverage by suburb, postcode, or electoral boundary and shows address counts and cost estimates before you book.
2. Book ahead. Australia Post's service guide asks for at least ten business days' notice. Standard service delivers nationally within 15 business days of booking. Premium is same-state only and delivers within 7 business days.
3. Print to size. Your item has to fit one of Australia Post's two size categories, set out below.
4. Lodge on time. Items are lodged in bundles on the date in your Booking Confirmation Advice. Standard same-state bookings lodge before 12 noon, five business days before the delivery week starts, and other-state bookings seven business days before.
5. Delivery. Australia Post delivers with the regular post during the nominated week.

Australia Post also distinguishes two booking types. A Regular booking covers, at minimum, all street and roadside delivery points in a suburb or postcode. A Select booking excludes those, sends to fewer than all available delivery points, or customises the area, which includes every booking made through Campaign Targeter.

Australia Post doesn't deliver advertising to letterboxes marked "No Unaddressed Advertising Material" or similar words. Only community notices from government, political, religious, educational, and charitable bodies reach those letterboxes.

Australia Post prices Unaddressed Mail on size, weight, destination, and service type, and frequent high-volume senders can negotiate contract rates. What a full campaign costs, with printing and tracking, is worked out by talking to our team or requesting a quick quote.

Plan around the peak period. For 2026, Australia Post isn't taking Premium bookings from 2 November 2026 to 3 January 2027, items heavier than 100g aren't available to non-contract customers, and there are no non-election deliveries in Victoria in the week starting 23 November 2026 because of the state election. Book early.

Which sizes does Australia Post accept?

Unaddressed Mail takes two size categories. Both must be rectangular and weigh up to 100g.

A6 (105 x 148 mm) and DL (99 x 210 mm) flyers fit the Small category. A5 (148 x 210 mm) is wider than 130 mm, so it books as Large. Anything outside these specifications needs Australia Post's approval before booking.

How do you track an Unaddressed Mail campaign?

You build the tracking into the item before it prints. Australia Post delivers in the week you booked, and the response is yours to measure, so give every campaign at least one of these:

• QR codes: a trackable QR code that leads to a campaign landing page lets you count scans and visits
• Unique URLs: a short, campaign-specific web address captures people who type rather than scan
• Promo codes: a code only this campaign carries ties in-store and online redemptions back to it, which suits retail and QSR offers

Tracked this way, a letterbox campaign reports next to your digital channels instead of on faith. Oppizi has tracked 1M+ conversions in Australia.

What is the difference between Unaddressed Mail and a letterbox drop?

The difference is who delivers and what proof you get. Unaddressed Mail is delivered by Australia Post with the regular post, while a Letterbox Drop is delivered by hand by flyer distributors on planned routes, with every mission verified by GPS and app check-in.

Both channels can start from demographics. Campaign Targeter can layer age, gender, and household income from ABS Census data onto your area selection to help you choose suburbs. Letterbox Drops add third-party demographic targeting on top of suburb, postcode, and custom-drawn areas. Either way, the flyer goes to a letterbox, not a named person. That's the job of Addressed Mail, which in Australia is built from your own customer data.

When does Unaddressed Mail make more sense?

When you want the widest reach with the least to manage: catalogues, store-wide sales, and awareness campaigns across several states, where a booked delivery week is precise enough.

When does a Letterbox Drop make more sense?

When you need to know exactly which streets were covered and when: a store opening, a launch in a new suburb, or an offer-led acquisition campaign you'll scale once the response holds up. For how a drop runs from brief to letterbox, see our guide to Letterbox Drops in Australia.

Can you run both?

Yes. You can book Unaddressed Mail for broad coverage and run Letterbox Drops in your priority suburbs, then compare response by area with a separate QR code or promo code for each channel.

What's the best letterbox distribution service in Australia?

It depends on the channel. Unaddressed Mail is delivered through Australia Post, booked directly or through Oppizi, and for Letterbox Drops the best fit is a tracked flyer distribution platform such as Oppizi, where every mission is verified by GPS and app check-in. For a side-by-side of providers, see our guide to the top flyer distributors in Australia.

How do you plan an Unaddressed Mail campaign with Oppizi?

With Oppizi, Unaddressed Mail runs end to end: printing, distribution through Australia Post, and tracking in one place, next to your Letterbox Drops in Oppizi OS. Creative Studio helps you build print-ready artwork with trackable QR codes built in.

Tell us your areas and your offer, and we'll plan the rest. Get started with Unaddressed Mail.