What Is Mailmark? A Simple Guide for UK Franking Machine Users

If you send business post in the UK, you have almost certainly seen the word "Mailmark" on your franking machine or a Royal Mail invoice. But what is Mailmark, why did it become compulsory, and what does it mean for the ink and labels you buy? This guide explains it in plain English for anyone running a mailroom or a small office franking machine.

What is Mailmark? A quick answer

Mailmark is Royal Mail's barcode standard for franked mail. A Mailmark franking machine prints a small 2D barcode next to the usual postage impression, and that barcode carries data Royal Mail uses to sort, track and verify your post automatically. In short, Mailmark is the modern, barcoded way of franking, and since 1 January 2023 it is the only type of frank Royal Mail accepts.

Why Royal Mail introduced Mailmark

Royal Mail moved its entire mail processing network over to barcode technology so that letters and large letters can be read by machine rather than sorted by eye. The 2D barcode in a Mailmark frank tells Royal Mail the class of service, the item weight band and the account that paid for it. That means faster sortation, fewer errors and better tracking, which is why Royal Mail phased out older, non-barcoded machines. You can read more about the wider price and service changes on the official Royal Mail website.

Is Mailmark still compulsory in 2026?

Yes. From 1 November 2022 non-Mailmark machines could no longer add postage credit, and from 1 January 2023 Royal Mail stopped accepting any franked mail without a Mailmark frank. So in 2026 a Mailmark franking machine is not optional, it is the standard. If you are still holding an older machine that is not Mailmark enabled, it can no longer be topped up or used to send Royal Mail post, and it will need replacing. Machines that are already Mailmark ready, such as the models covered in our guides to the FP Mailing Postbase Vision M2 and the Quadient iX-1 Series, need no action.

How much does Mailmark franking save versus stamps?

The biggest day to day benefit is price. Franking with a Mailmark machine is cheaper than buying stamps for the same items. From 7 April 2026, a first class letter up to 100g costs £1.77 when franked with Mailmark, compared with £1.80 for a stamp. A second class letter up to 100g costs 88p franked against 91p as a stamp. Those few pence per item add up quickly across hundreds or thousands of letters, and the gap is wider still on large letters. For the full breakdown of current prices, see our 2026 Royal Mail postage rates guide.

What a Mailmark frank looks like

A Mailmark impression has three main parts: the Royal Mail cruciform logo and postage value, your advertising or return address slogan if you use one, and the 2D data matrix barcode that makes it Mailmark. The barcode is usually a small square block of dots. Because that barcode has to be scanned by Royal Mail's equipment, print quality matters far more than it did with older franking. A clean, crisp frank scans first time, while a faded one can be delayed or surcharged.

Does Mailmark need special ink?

Mailmark machines use the same Royal Mail approved red fluorescent ink as most modern franking machines. There is no separate "Mailmark ink", but there is a very good reason to use fresh, genuine or high quality compatible cartridges: the barcode. If you want to understand the trade offs, our comparison of original versus compatible franking ink walks through what to look for. You can find the correct cartridge for your model in our franking machine supplies range, organised by brand for Pitney Bowes, Quadient, FP Mailing, Neopost and Frama.

Keeping your Mailmark frank scannable

Because the whole system relies on a readable barcode, ink care is central to trouble free franking. A few simple habits keep every frank sharp:

• Replace cartridges before they run dry rather than pushing them to the last drop, since a starved print head is the most common cause of faint franks. Our step by step guide to changing an ink cartridge makes this quick.
• If franks start printing pale or with white lines through the barcode, act early. See why franking machines print faint or streaky and how to fix it.
• Store spare cartridges correctly so they do not dry out before use.
• Run the machine's built in print head cleaning cycle if the barcode looks patchy.

Mailmark labels for awkward items

Not everything fits through a franking machine. Thick packets, parcels and stiff envelopes are franked onto a self adhesive label instead, which carries exactly the same Mailmark frank and barcode as a printed envelope. Keeping approved labels in stock means you never have to hold post back. You can browse Mailmark friendly franking labels and supplies alongside your ink, and if you are unsure when to reach for a label our article on when to use franking labels covers the rules that stop mail being rejected. For posting envelopes designed to work neatly with franked mail, see our approved meter posting envelopes.

The bottom line on Mailmark

Mailmark is simply the current standard for UK franking: a barcoded frank that is faster for Royal Mail to process and cheaper for you to send than stamps. The machine does the clever part automatically, so your job is mainly to keep it fed with fresh, approved ink and the right labels so every barcode scans first time. Stocking the correct franking ink cartridges for your model is the easiest way to protect your postage discount and avoid rejected mail.

Frequently asked questions

What is Mailmark on a franking machine?

Mailmark is Royal Mail's barcode standard for franked mail. A Mailmark franking machine prints a 2D barcode alongside the postage impression, which lets Royal Mail sort and track your mail more accurately and unlocks the lowest franking prices.

Do I still need a Mailmark franking machine in 2026?

Yes. Royal Mail decertified non-Mailmark franking machines from 1 January 2023, so all franked mail must now carry a Mailmark frank. If your machine is not Mailmark enabled it can no longer add postage or be used to send Royal Mail post.

Is Mailmark franking cheaper than stamps?

Yes. From 7 April 2026 a first class letter up to 100g costs £1.77 with Mailmark franking compared with £1.80 for a stamp, and a second class letter costs 88p franked against 91p as a stamp. The savings grow with higher posting volumes.

Does a Mailmark machine use special ink?

Mailmark machines use standard Royal Mail approved red fluorescent ink, the same type used across most franking machines. The key is to use fresh, approved ink so the barcode and frank print clearly enough to scan.

What happens if my Mailmark barcode does not print clearly?

A faint or streaky barcode can be rejected or delayed because Royal Mail's scanners cannot read it. Replacing a low or dried out ink cartridge and cleaning the print head usually restores a crisp, scannable frank.

Ready to keep your Mailmark machine running perfectly? Explore our full range of franking machine ink and labels and order the exact cartridge for your model today.