What is a Royal Mail Mailmark 2D barcode?
Mailmark 2D is a Royal Mail barcode based on Data Matrix. It carries a fixed-format Mailmark data string that includes information such as the format, version, class, supply chain ID, item ID and destination, plus optional customer data.
Royal Mail uses Mailmark to sort, track and report on business mail. Mailmark also exists as a 4-state barcode, while the older RM4SCC holds only the postcode and delivery point.
To post real mail with Mailmark, you need a Royal Mail agreement and an assigned supply chain ID, and your data must follow Royal Mail's specification. The generator encodes the data string you supply.
What data can Royal Mail Mailmark 2D hold?
A Mailmark data string in Royal Mail's fixed format, for example JGB 012100123412345678AB19XY1A 0 followed by padding and optional customer data.
Recommended size
Follow Royal Mail's Mailmark guidance for symbol size, quiet zone and position on the item, and test-print before a large mailing.
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How to Create a Barcode in 3 Steps
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Select a category on the left (e.g. Linear Codes), then the exact type like Code-128.
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Exact mm sizes, label sheets (Avery, A4, 4×6 thermal).
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Frequently Asked Questions
It is produced by mailing software using IDs from your Royal Mail agreement. The generator encodes what you enter but cannot create valid IDs.
It is built on Data Matrix, but the content must follow Royal Mail's Mailmark structure.
Use whichever your Royal Mail service specifies. Mailmark carries far more data than RM4SCC.