If you run a franking machine, the ink you buy is not optional: it is the difference between mail that Royal Mail accepts and mail that gets returned. The short answer is that Mailmark and smart franking machines use Royal Mail approved blue ink, while older standard (analogue) machines used red fluorescent ink. Fitting the correct approved cartridge keeps every imprint scannable, protects your machine's printhead, and stops rejected post from landing back on your desk. This 2026 guide explains the colours, the genuine-versus-compatible question, and how to make each cartridge go further.
Why the ink colour matters
Royal Mail reads the mark your machine prints, so the ink has to meet its optical standards. Newer Mailmark franking machines print a 2D barcode alongside the postage indicia, and that barcode is designed to be read in blue. Older analogue meters produce the traditional town-circle imprint in red fluorescent ink. Using the wrong colour, or a non-approved ink, can cause the mark to fail scanning, which risks surcharges or returned items.
Since every non-Mailmark meter has now been decertified by Royal Mail, the vast majority of UK businesses are running Mailmark machines and should be buying approved blue ink. If you are unsure which category your machine falls into, check the model against our supplies collections or ask before you order, because putting red ink in a machine that expects blue will not produce a compliant imprint.
Genuine versus compatible cartridges
This is the question that saves businesses the most money. Manufacturer (OEM) cartridges from the likes of Pitney Bowes, Quadient and FP Mailing are reliable and Royal Mail approved, but they carry a premium price. Good quality compatible cartridges are also Royal Mail approved, deliver the same number of impressions, and can cost up to 50% less than the branded equivalent.
You are well within your rights to choose. Under long-standing Office of Fair Trading guidance (OFT 2005), every franking machine user is free to buy consumables from any supplier, not just the machine manufacturer. That is exactly why our compatible franking machine ink cartridges exist: identical Royal Mail approved performance, a much friendlier price. The one rule worth repeating is to buy from a Royal Mail approved supplier rather than an unknown marketplace seller, because a bargain cartridge that clogs a printhead is no bargain at all.
Matching the cartridge to your machine
Franking ink is not universal. Each machine family uses a specific cartridge shape and ink formulation, so the safest approach is to shop by manufacturer and model. Green Franking groups supplies exactly this way:
- Pitney Bowes inks and labels for the SendPro, DM and Connect+ ranges.
- Neopost / Quadient inks and labels for the IN, IS and iX series.
- FP Mailing inks and labels for the Postbase range.
- Frama inks and labels for the Matrix series.
If you are still shopping for the machine itself, remember that Green Franking specialises in supplies rather than hardware. For buying, leasing or servicing an actual franking machine, our sister company Mailcoms handles the equipment side, so you can source the meter from them and the ongoing ink and labels from us.
Making your ink last longer
Franking cartridges are inkjet based, which means the enemy is a dried-out or blocked printhead. A few simple habits protect your investment:
- Store spare cartridges upright, in their sealed packaging, away from direct sunlight and radiators. Room temperature is ideal.
- Keep the machine powered and let it run its automatic head-cleaning cycle rather than pulling the plug at night, as regular use keeps ink flowing.
- Order a replacement before you fully run dry, so a weekend of empty nozzles does not leave ink crusting in the head.
- If imprints look faint or streaky, run the machine's built-in printhead clean before assuming the cartridge is finished.
Batching your outbound post also helps. Franking a full tray in one session uses ink more evenly than firing off single items throughout the day, and it pairs neatly with the cost savings franking already gives you over stamps.
The cheaper, greener option: refill and recycle
Empty cartridges do not have to go in the bin. Green Franking runs an ink resetting, refilling and recycling service that gives your existing cartridge a second life, trimming both cost and plastic waste. It is a natural fit if you already care about the carbon footprint of your mailroom, a theme we explored in our guide to sustainable mailing for small businesses. Choosing compatible cartridges and recycling the empties is one of the easiest wins available to any UK mailroom in 2026.
Why the right ink pays for itself
Franking is already the cheaper way to send post. Following the rate change that took effect on 7 April 2026, a Mailmark franked First Class letter costs about 3p less than the equivalent stamp, and Royal Mail's Mailmark Focus tariff shaves a further 2p off every First and Second Class letter for franking customers. None of those savings count for anything, though, if your imprint fails to scan because of the wrong or poor quality ink. Buying the correct approved cartridge is the small step that unlocks every other saving, and confirms Royal Mail's own figures on the Mailmark savings for your business.
Frequently asked questions
Do Mailmark franking machines use blue or red ink?
Mailmark and smart franking machines use Royal Mail approved blue ink, because the Mailmark 2D barcode is designed to be scanned in blue. Only older standard analogue meters use red fluorescent ink. Always match the ink colour to your machine type.
Are compatible franking ink cartridges Royal Mail approved?
Yes. Good quality compatible cartridges from a reputable supplier are Royal Mail approved and produce the same number of scannable impressions as genuine cartridges. The main difference is price, with compatibles often costing up to 50% less than branded OEM ink.
Is it legal to use non-manufacturer ink in my franking machine?
Yes. Under Office of Fair Trading guidance (OFT 2005), franking machine users are free to buy consumables from any supplier, not only the machine's manufacturer. Using approved compatible ink does not affect your Royal Mail franking account.
How do I know which cartridge fits my machine?
Franking cartridges are model specific, so shop by manufacturer and machine family. Green Franking lists inks and labels by brand for Pitney Bowes, Neopost / Quadient, FP Mailing and Frama, so you can pick the exact cartridge for your model.
How should I store franking ink cartridges?
Keep spare cartridges sealed, upright and at room temperature, away from direct sunlight and heat sources. Order a replacement before the current one runs dry to avoid the printhead drying out, and run the machine's cleaning cycle if imprints start to look faint.
Where can I buy a franking machine rather than just supplies?
Green Franking focuses on supplies such as ink, labels and envelopes. For buying, leasing or servicing the machine itself, its sister company Mailcoms handles franking machine hardware, so you can source the meter there and your ongoing consumables from Green Franking.