What is PAF and how does it work?

Data /  26 September 16 / by Dale Brett    
What is PAF and how does it work?

If you have used a mailing house in the past to send out a direct mail campaign using names and addresses from a data file then you will probably have heard of the word PAF, especially connected with Royal Mail; but what is PAF and why should you use it?

PAF stands for Postal Address File and it is a collection of valid UK postal addresses that was created and is maintained by Royal Mail. Each address on PAF is made up of different address parts, such as the town, county, and postcode, and combining the address parts in the correct order reveals what Royal Mail consider the PAF valid address.

Data Cleaning

Depending on where you obtain your mailing data you may have accurate, clean data or you may have inaccurate, dirty data.

Dirty data may have addresses that are incorrect, they may have a missing postcode, the house number may be wrong, or the town may be spelled incorrectly; in each of those cases the mail may not reach the destination.

Mailing data can be corrected using PAF correction software; various parts of the original address, such as the postcode, town, or premise, are used to try and find a match in the PAF collection, and if a matching address can be found then the original address can be replaced with the PAF valid version resulting in a cleaner data file. Whether a match can be found depends on the original address and the accuracy of the matching software.

Some mailing houses offer manual PAF correction, where a person will look up addresses that cannot be matched automatically and use their judgement to find and correct the invalid address, though services such as these are normally quite expensive.

Often, addresses may not be considered PAF valid because of simple spelling errors, or perhaps somebody has named their house and they do not refer to it using the official building number, in these cases the mail will reach its intended destination and the data does not need correcting.

Sorting Mail for Postage Discounts

When you use a postal provider to send a printed campaign of a particular size you have the option to sort your mailing by area and then bag up the mail in particular order, which will earn you a discount on your postage cost. This is done so that the different bags can be delivered directly to the correct distribution centre without the postal provider having to examine each piece of mail individually.

There are many sort options and the content of your creative and the number of mail items determine which options are available to you, but in order to qualify for discounts the postal provider has to be certain that the addresses you have identified as belonging to a particular area are valid, and they do this using PAF.


Each address on PAF has what is called a Delivery Point Suffix, or DPS; the DPS is a combination of a single number and a single character, e.g. 1D.

In combination with the postcode, the DPS identifies a unique address within the UK. Mailing files can be matched against PAF in order to find their DPS without having to replace the original address information; if an address cannot be matched against PAF it is given a default DPS of 9Z flagging it as unidentified.

Mailing files must have a minimum percentage of addresses with an identified DPS in order to qualify for discounted services with the match level depending on the type of service required.


PAF allows you to improve your mailing data with accurate addressing which in turn allows access to discounts with postal providers, however it is important to remember that PAF is a licensed product that is owned by Royal Mail who charge data processing bureaus a fee to have access to and use the data, a cost that will be passed onto the end user.

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