Understanding and minimising postal costs.

You've produced a beautiful creative direct mail campaign, you know it's going to be super effective, but have just found out how much it's going to cost to post it out. Gulp! Back to the drawing board...

If this has been you, or you're currently in the throws of putting together a direct mail or postal campaign, below are some ways to make sure your postal budget goes as far as possible and your design makes the best possible use of the mailing guidelines and minimises postal costs.

Postal size and weight

When posting large volumes of mail (usually over 4,000 letters or 1,000 packets, but there are exceptions), discounts are generally available from postal carriers (e.g. Royal Mail). Royal Mail’s Pricing in Proportion (PiP) means the size and shape, as well as the weight, should be considered at design stage to ensure it remains economical for the items to be delivered.

The main categories are:


For example: most cards, postcards and bills

Length 240mm max
Width 165mm max
Thickness 5mm max
Weight 100g max





Large letter

For example: most A4 documents and magazines

Length 353mm max
Width 250mm max
Thickness 25mm max
Weight 750g max





Packet (i.e. anything else)

For example: most gifts, posters and large books

Length over 353mm or
Width over 250mm or
Thickness over 25mm or
Weight over 750g





Down Stream Access (DSA)

It is possible through the use of Down Stream Access (DSA) to gain greater savings on your postage costs on top of the savings provided by using Royal Mail’s Mailsort products. These savings are possible as a result of more work being undertaken upfront during the data processing, pre-sorting and presentation of the mail, so that less work has to be done by the postal provider to get the items of mail into the postal system in the correct way. DSA can only be used on 2nd class work, not 1st class or economy. The unit costs achievable are generally in line with that of the economy service with a much better delivery timeline. There are several DSA providers who are able to provide this service including The Delivery Group, One Post, UK Mail and Whistl.

Mail Made Easy

The Royal Mail offer the “mail made easy” program. This program was set up to promote Direct Mail and offers incentives to new customers to start advertising via Royal Mail services.

International Mailing

If you are posting overseas, it is also possible to work with consolidators and Royal Mail to get the best international costs for mailing including signed-for and tracked services.

Data Sorting

There are a number of ways databases for mailing can be sorted in order to maximise postal efficiency and, therefore, cost. Some of the common ways are:

High Sort

High Sort is a product which allows postage discounts on letters (over 4000 records), large letters (over 1000 records) and packets (over 1000 records). It is used for products which are classified as “non-machineable” such as open edge products (e.g. self-mailers), packets, poly bags etc. Generally, discounts are less than Low Sort products and the work is normally presented in mail bags with Mailsort tickets. The data does not need to go through the Postcode Address File (PAF) or have a high Delivery Point Sequence (DPS).

Low Sort

A minimum of 4,000 letters, or 1,000 Large Letters in a single mailing. Low Sort is for mail that meets Royal Mail’s machine-readable specification. To qualifiy, mail needs to be sorted to Royal Mail’s Low Sort specification and addresses readable so that mail pieces can be routed by their sorting machines to achieve maximum savings. Available Low Sort options are:

  • Mailmark - Mailmark replaces the old Royal Mail Customer Barcode (CBS) service and uses a 2D barcode that carries much greater information on the sender, mail piece and address details. This is used by Royal Mail to track each individual mail piece and allow the mail items to process better through their machinery.
  • OCR – Using Optical Character Recognition (OCR) Royal Mail are able to machine scan the mailing and process items much more quickly and efficiently. With OCR mail you do not need to have any kind of barcode on the mailing item, but the savings are less than Mailmark. From a design point of view, you need to allow for areas to be free of print for this service.
Poll Sort

A mailing scheme used for the mailing of polling cards. This product is the same as the old Walksort product which was discontinued by Royal Mail a number or years ago. Poll sort was introduced because Royal Mail could not offer Mailmark discounts on poll cards but still wanted to offer a cheaper alternative to standard High Sort.

Advertising Mail

Ad Mail is a product offered by Royal Mail to provide greater discounts to clients who use mailing to advertise products and services, or charities who use it to raise money or support. It is one of Royal Mail’s incentives to encourage customers to use direct mail instead of digital marketing. To qualify, a mailing item must contain a minimum level of advertising. It can be used with all Mailsort products and standard tariffs, but is dependent on minimum volume levels.

Sustainable Mail

Additional discounts can be obtained through Sustainable Mail. Sustainable Mail can only be used in conjunction with Ad Mail and requires the mail items to use FSC or recycled products. Conditions are also placed on the amount of ink used and that additional data work may need to be carried out.

If you need any specific help or have any questions about mailing or have a mailing requirement, please contact us, we'd love to help. Or if you would like to find out more about how we can help you, have a look at our mailing services.