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Door Security

Letterbox Guards — Prevent Lock Fishing

A letterbox guard stops burglars from reaching through your letterbox to grab keys or operate door handles. A simple, affordable upgrade that blocks a common burglary technique.

Internal letterbox guard cage installed behind a front door letterbox

Key Features

  • Blocks fishing and manipulation tools
  • Allows normal post delivery
  • Internal metal cage or cowl design
  • Fits behind existing letterbox
  • Quick 15-minute installation
  • Works with all door types
  • Affordable security upgrade

What Is Letterbox Fishing?

Letterbox fishing (also called letterbox manipulation) is a burglary technique where a criminal pushes a wire, hook, or flexible tool through your letterbox to reach door handles, keys left on a nearby hook or table, or even the lock mechanism itself. It's quick, quiet, and surprisingly common — especially in areas with terraced houses and uPVC doors where letterboxes are close to the handle.

How Letterbox Guards Work

A letterbox guard is a metal plate or cage that fits behind your letterbox on the inside of the door. It allows post to drop through normally but blocks any tools from being pushed through to reach further inside. There are several types:

Internal Letterbox Cage

A wire or metal mesh basket that attaches behind the letterbox opening. Post falls into the cage and can be collected easily. The cage prevents anything from being pushed through and reaching the door handle or lock.

Letterbox Cowl / Restrictor

A metal plate that covers the back of the letterbox, leaving just enough room for post to slide through but blocking tools from reaching further. More discreet than a cage and equally effective.

Letterbox Draught Excluder with Security Function

Combined draught excluder and security device — blocks cold air AND fishing attempts. A practical dual-purpose option.

Do You Need a Letterbox Guard?

You're at higher risk if:

  • Your letterbox is on the same door as your main lock (most front doors)
  • Your door handle is within arm's reach of the letterbox
  • You keep keys on a hook or table near the front door
  • You have a uPVC door where the handle lifts to lock — a tool through the letterbox can lift the handle
  • You live in a terraced house or ground-floor flat with direct street access

Other Protective Measures

Alongside a letterbox guard:

  • Never leave keys near the front door — hang them out of reach of the letterbox
  • Consider a keyless handle — some uPVC doors can have the external handle removed so it can only be operated from inside
  • Upgrade your lock — an anti-snap Euro cylinder with a lockable thumb-turn means the lock can't be operated without the key, even if someone reaches the mechanism

Installation

Most letterbox guards can be fitted in 10-15 minutes. They screw directly into the inside of the door around the letterbox opening. For the most secure fit, especially on uPVC doors where screw holding can be weak, professional installation ensures it stays in place under force.

Get a Letterbox Guard Fitted

We supply and fit letterbox guards as part of our local locksmith service. It's one of the most affordable and effective security upgrades you can make.

Call 0330 133 1339 for advice and fitting across Coventry, Sheffield, Colchester, and all our service areas.

Want This Installed?

Our locksmiths carry these products on their vans — same-day fitting available

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