Guide to mailsort

What is mailsort?

In layman’s terms mailsort is the process required to achieve big postal discounts for UK addresses. It is possible to achieve savings of 60% against the cost of 2nd class stamps.

The first step: your database needs to be run through a computer program that looks at the postcodes and uses them to generate what is called a “mailsort code”. We have the program to do this.

Your database is then sorted by this “mailsort code” and printed out in this order.

The mailing needs to be kept in this sequence throughout the stuffing process and presented to the Royal Mail in mail-bags in that order. Special mailing labels are added to the mail-bags to tell Royal Mail where the bags are heading to.

Generally speaking, it is not a process to be undertaken in-house. Any deviation from the strict guidelines and you lose the postage discount that you are trying to achieve.

Mailsort is not widely known to the British public and the code is not written as part of the address; rather it appears elsewhere on the envelope or label as a 5 digit number. Although the majority of people in the UK use the postcode, the mailsort code is now used for automated sorting.

Unlike posting by ordinary mail it is possible to specify service levels other than 1st or 2nd class with longer delivery times offered called ECONOMY (was called mailsort 3). Two main Mailsort products are available – known as lowsort and highsort– each based on the customer’s ability to sort into increasingly smaller geographical areas.

How many items do I need to post?

You can earn savings by sorting your mail and ensuring your addresses are accurate. You must provide a minimum of 4,000 letters or 1000 large letters in a single mailing to qualify for mailsort discount.

Low Sort option – cheapest method

For mail that meets machine-readable specification, sort your mail to a maximum of 88 ways and ensure your items can be read by sorting machines to achieve maximum savings.

  • Sort up to 88 selections as detailed in the Royal Mail Selection Files (the new name for the Mailsort Database)
  • Ensure that 90% of your mail has postcode and address accuracy using either OCR font or barcode (for letters only).

High Sort option – more expensive but less rigorous

  • Sort up to 1,525 Direct Selections or 88 Residue Selections as detailed in the Royal Mail Selection Files
  • Ensure that 90% of your mail has postcode and address accuracy
  • You must have a minimum of 50 letters or 10 large letters for a Direct Selection. The rest goes in to residue which is more expensive rate.

Typical Royal Mail mailsort delivery schedules: 

Economy service : 4 day typical delivery
2nd class: 2 day typical delivery
1st class: Next day typical delivery

Downstream access (DSA):

The vast majority of mail in the UK is delivered to the door by the Royal Mail (TNT are trialling some London postcodes with direct delivery currently and DX also deliver direct to selected business addresses).

Downstream access companies (such as TNT, UKMAIL, CITIPOST) will take the sorted mail from the mailing house, add it to the rest of their mail and then present it to Royal Mail the next day. Royal Mail are then obliged to deliver it the following day. So mailsort via downstream access is a 2 day delivery. Unsorted mail takes 3 days to land following collection of the mail from the mailing house, as the DSA company will attempt to sort this before they give it to Royal Mail.

What we have found it can be very difficult to get LOWSORT to pass the machine reading process if you present it via DSA. It would appear that Royal Mail closely scrutinises LOWSORT mail from DSA’s, looking for reasons to fail it and revert it back to HIGHSORT residue prices.

If you present LOWSORT directly to Royal Mail it almost always passes the requirements, so long as the basic tap-test rules are followed and the clearzones are ‘clear’ on the envelopes.

What is a tap-test?

A personalised item inserted into a window envelope is tapped in all 4 directions to ensure that the address remain fully visible in all directions and that no other text or graphic can be seen that could affect the machine reading process.

What are clearzones?

There are 2 areas on envelopes that Royal Mail likes to print barcodes on to aid with sortation, usually the bottom right and then about 5cm above it on the right also.


What qualifies as Advertising Mail?

Mailings made up of a largely uniform message to all addressees with the purpose of promoting the sale or use of products or services; those that encourage contribution to, or support of a cause, are classed as Advertising Mail. We ask all Advertising Mail users to send us a sample of their mail piece for approval prior to issuing a licence for each mailing.
This will typically give you an extra 2p per item discount against both highsort and lowsort pricing.

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