The Crime Prevention Website


When working for Secured by Design and writing their design guides I considered the crime problems associated with letter plates in doors. Letter plates are those oblong shaped flaps where the postman puts the mail and should not be confused with letterboxes, which are containers that are generally fixed to an external wall or onto a timber or metal post (esp. mailbox in the USA and Canada). A letterbox can be fixed to the back of a door where it is fed via a letter plate, but this is not that common. 

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Looking at the crime data for England and Wales it is a sad fact that something as simple as a small hole in the door can lead to some very serious crime indeed.  It is perhaps worth mentioning that most of Europe does not incorporate letter plates into their doors. Yes, there will be some who do, but according to a European Committee dealing with letter plates of which I was a member (deep joy), it seems to be a peculiarity for the UK, Ireland the Scandinavian countries and to some extent, the Netherlands.  This may have had something to do with legislation in these countries requiring the mail to be delivered into the dwelling.

The seven main problems with letter plates

Evidence of occupancy

How many times have we come home to find a freebie newspaper or leaflets sticking out of the letter plate?  One annoying factor not associated with crime, is that in the winter this ill considered deed lets the cold air into the house (or lets the warm air out).  Straightaway we can see that from a sustainability point of view they are not such a good idea.  The main point here though is that a newspaper stuck in a letter plate might indicate that nobody is at home.  It could be this small visual clue that puts the idea of burglary into the mind of the thief.

Evaluating the target   

Evaluating a target or ‘casing the joint’ (an expression I never heard used in all my years in the police) can be assisted by looking through the letter plate.  Can the thief hear people inside the home or can he see the car keys on the hall table?  


The term ‘fishing’ describes the action of putting a rod and hook or arm and stick through the letter plate in order to steal something in reach.  This technique normally leads to the theft of the house and car keys left on a hall table.  With the keys they will let themselves into the house and steal from it or steal the car or do both.  It is of interest to note that this problem only started to occur in any great numbers after the security of motor vehicles improved.  With immobilisers being fitted as standard and with many people installing vehicle tracking devices to their cars, a car thief was forced to steal the keys (another example of the ‘arms race’).  In fact, the term ‘fishing’ has only come into crime language in the last ten years or so to describe this method of theft. 

Lock manipulation

This method of burglary is actually pretty old and it refers to the technique of putting an arm (a pretty thin one, often belonging to a juvenile) though the letter plate to access the turn knob on the back of a lock.  This is the way that people will break into a house converted into flats where there is often a single nightlatch on the street entrance door.  The other growing problem concerns the opening of multipoint locking mechanisms.  If you have a door that has multipoint locking with what’s called a ‘split spindle’ on the door handle then I know that many of you do not throw the bolts (by lifting the handle) and key lock it at night.  If you don’t do this then you can open the door by just pushing down the internal handle.  Burglars know this and they will tour an area putting a stick through people’s letter plates to see if they can open the door like this.   The ones most at risk are those where the letter plate is in the centre of the door, about 200mm away from the handle.  Finally, another technique involves the use of electrical cable.  The cable is folded in half with a loop at one end which, with some skill, is put through the letter plate and placed over the turn knob on the back of a nightlatch.  Once in place it is pulled tight and then one half is gradually pulled.  This turns the knob and opens the door.

Door pulling

Thanks to my plumber for this one! Although rare, there have been instances where a grappling iron or something similar has been inserted through the letter plate to grip onto the inside of the door.  This is then attached by rope or chain to a large vehicle and the door is literally pulled from its frame.  This type of forced entry can only really be expected to occur at a dwelling that is both remote from neighbouring properties and has sufficient space for the vehicle to manoeuvre.

Vandalism including flooding

Nasty things have been pushed through letter plates, including dog’s muck, shaving foam and eggs (Halloween) and hose pipes with the water turned on!  (You can buy locking outside taps by the way)


By far the most serious crime to occur because of letter plates is arson, which has led to many injuries and some deaths in the UK.  According to the fire service, most domestic arsons (around 90%) involve the letter plate through which petrol or similar fuel is poured followed by a burning rag or firework.  Very often the fuel falls onto a carpet, which aids the burning, and the worst aspect of this is that the fire is at the front door, which most of us would use as our means of escape in an emergency.  At the less serious end of intentions, but nevertheless with extremely serious outcomes, are people putting fireworks through people’s doors for ‘a laugh’.  Every year on Bonfire Night, there seems to be an incident where somebody has been injured or even died because some idiot has done this stupid thing.  

Solutions for houses, maisonettes and houses in multiple occupation

Letter plates in doors

Security Specification for Letter Plates

If it is your intention not to use a secure letterbox, but to retain a letterplate in your door then please look for products that have been successfully tested to the specification described below:

In May 2012 the Door and Hardware Federation published an important Technical Specification for the testing of letter plates, entitled TS 008:2012 'Enhanced security and general requirements for letter plate assemblies and slide through boxes' A PDF version of the document is available from DHF Online at this link.

This technical specification, which employs human intervention testing, provides a method of evaluating a letter plate's resistant against opportunist attacks aimed at removing delivered mail (Test A) or items, such as a set of keys (Test C) back through the letter plate, operating a thumbturn on the inside of the door (Test B) and potential attack by arson (separate testing). The products also undergo a variety of general performance tests to assess, amongst other things, its strength and its resistance to corrosion and water penetration.

Letter plates that are tested for their resistance to arson attack will have a box, or other container, fixed on the back of the letter plate to contain the potential fire either from accelerants or fireworks, etc. 

Products that comply with tests A and B are classed as Grade 1 (Security) and products that comply with A, B and C are classed as Grade 2

Successfully tested products will be clearly labelled as shown in the PDF document referred to above. 

Letter plate deflectors

At the very least a letter plate deflector (or cowling or hood) needs to be fixed to the back of the door around the letter plate to prevent arms, sticks and fishing rods being poked through.  If your door has multipoint locking then you must remember to engage the locks at night and turn the key in the cylinder.  You don’t often find letter plate deflectors in the DIY stores, but you can get them from locksmiths and from some websites.  Do leave the key close to the door in case you need it in an emergency. 

Letter plate (letter flap) locks

The next step up from this is to fit a letter plate lock.  This is a hood that fits directly over the top of the inside of the existing letter plate.  It has an inner flap, which you can lock at night that will prevent anything from being pushed through.  I do not know how effective this system is against an arson attack, but it would certainly make it more difficult to pour large amounts of accelerant through the plate and it would certainly stop many firework attacks.  That said, you do have to remember to use it every night; make it part of your locking up routine.  

Fire resistant containers and bags

If arson is a threat and you want or need to keep the letter plate and a locking letter plate hood is no good for you then you’ll have to fit a special steel container or fire retardant material bag onto the back of the letter plate.  Some of these containers include a fire extinguisher.  Obviously, the container or bag has to fit over the entire letter plate and have a good seal against the door.  A particular advantage of the material bag is that it takes up very little room and will not obstruct the opening of your entrance door if the hallway is small.  You can find these products on the web, but you need to find one that has had some independent testing conducted upon it, preferably using the security and test specification described above. 

External letter boxes

It seems to me that the most sensible thing to do, if it’s practical, is to block up the letter plate and instead have your mail delivered into a secure letter box fixed to the wall next to the entrance door.  This is something you can do now with an existing door or, if you’re going to replace your entrance door, do it then and ask the door supplier for a door without a letter plate. Do make sure that your letterbox complies with  BS EN 13724: 2002 Postal services. Apertures of private letter boxes and letter plates. Requirements and test methods. This is because you’ve got to provide the postie with one of the right size.  You can now purchase a letter box certified to the new Door and Hardware Federation's security specification for letter boxes (see below)

Security Specification for Letter Boxes

In May 2012 the Door and Hardware Federation published an important Technical Specification for the testing of letter boxes, entitled TS 009:2012 ‘Enhanced security and general requirements for letter box assemblies that are free standing or surface mounted and where mail is retrieved from the same side as delivery’. A PDF version of the document is available from DHF Online at this link.

This technical specification, that employs human intervention testing, provides a method of evaluating a letter box’s resistant against opportunist attacks aimed at removing the letter box and or items within it and potential attack by arson. 

Products that conform to the requirements of the technical specification are classified and labelled according to their resistance to manual attack (Grade 1 = 30 seconds, Grade 2 = 60 seconds), the type of letter box (wall mounted, free standing or both), a strength test, its locking provision and resistance to corrosion, water penetration and arson attack.

Since publication DAD Ltd has become the first letter box manufacturer to achieve a Grade 2 resistance rating for one of its products using this specification. (See News item for DAD Ltd)


June 2015. I am really pleased to announce that DAD UK Ltd have joined The Crime Prevention Website with their secure letterbox and you can find them listed in our Directory

Sixty seconds of resistance against manual attack doesn’t seem to be very long, but as the tests are conducted under laboratory conditions by engineers who have the opportunity to thoroughly examine the product beforehand it is likely that the product will resist ‘real’ attacks in the field for at least this amount of time and probably longer. The specification will also have balanced the requirements against the realities of mail theft.  Most of our letter boxes are located to the front of the building and generally benefit from overlooking from other properties.  There is therefore a limit to how long an opportunist thief would be willing to attack the box.  If the specification were to be any more onerous manufacturers would find it extremely difficult to make a letter box that they could actually sell.  In special circumstances of very high risk it is conceivable that a letter box could be constructed against the security specifications of LPS 1175 as mentioned elsewhere.

This new security specification for letter boxes is a very welcomed addition to the growing stable of domestic and commercial building security standards and now DAD Ltd have produced the first TS009 box I would expect others to follow in the next few months.

Solutions for blocks of flats 

If you have your mail delivered straight to your flat door through the letter plate then the solutions above are just the same for you.  However, if you rent the flat then you’ll need to get permission from the owner to make the improvements, particularly if you want to put a letter box on the outside wall, which actually may not be practical.

In many modern blocks the mail is delivered into a ‘through-the-wall’ letter box.  The box is then emptied by the residents from the inside, behind the secure entrance door, and there is no need for the postie to enter the block.  This also makes his or her job a lot easier.  In some blocks the mailboxes are placed inside the entrance hall or foyer, which means that the postie does have to come into the block, usually between set times using the trades button.  In a lot of cases there is an additional accessed controlled door to the lift lobby and staircase, so that if someone who is up to no good gets into the hallway using the trades button at least there is another barrier before they can get to the individual flat entrance doors.  This double door arrangement is known as an ‘airlock’. So, if mail delivery is a problem, the next time you attend a residents meeting you might want to bring these matters up.

Updated March 2016