Letterbox Security Guide¶

Complete guide to letterbox security for UK homes covering anti-fishing plates, internal cages, letterbox brushes, and strategies to prevent key theft through the letterbox.

Letterbox Security Risks¶

The letterbox is one of the most overlooked security vulnerabilities in UK homes. Letterbox fishing using a tool inserted through the slot to hook keys from nearby hooks or tables is a documented burglary method. Thieves also use the letterbox to spray aerosol deterrents that prevent alarms from detecting smoke. The ONS reports that a significant percentage of burglaries involve keys being retrieved through the letterbox. The first defence is key management never leave keys on hall tables, hooks near the door, or in visible kitchen drawers. Install a key hook inside a cupboard, drawer, or wall-mounted key cabinet away from the front door.

Letterbox Security Products and Installation¶

Several products address letterbox security. Anti-fishing plates mount inside the letterbox and prevent tools reaching through. Murray and London Door Company offer plates from 15-40. Letterbox cages enclose the interior of the letterbox with a mesh box that catches mail while preventing access. Available from 10-25 at Screwfix. Magnetic letterbox covers offer temporary security when away. Brush strips fit inside the letterbox slot, reducing visibility through the opening while still accepting mail. Yale letterbox brushes cost 8-12. For maximum security, install a letterbox that opens to the exterior and uses a brush system that prevents tool insertion. External mailboxes totally eliminate the letterbox vulnerability, mounted on the wall outside the door with a slot for postal delivery.

Specifications and Comparison¶

Product	Security Level	Cost	Ease of Installation
Anti-fishing plate	High	15-40	Medium
Letterbox cage	Medium-High	10-25	Easy
Brush seal strip	Low-Medium	8-15	Easy
Magnetic cover	Low	5-10	Easy
External mailbox	Very high	40-120	Medium

FAQ¶

Can burglars really get keys through a letterbox?: Yes. Letterbox fishing using thin tools inserted through the slot is a well-documented method. Keep all keys at least 1.5 metres from the letterbox and use an anti-fishing plate.
What is a letterbox brush and does it help security?: A letterbox brush fits inside the slot with bristles that block visibility and make tool insertion difficult. While not as secure as an anti-fishing plate, it offers an improvement over an open slot.
Should I get an external mailbox instead?: External mailboxes eliminate the letterbox vulnerability entirely and are strongly recommended for high-value properties. They cost 40-120 and require wall mounting near the front door. For more information see our Key Safe Installation Guide UK.

Last updated: 2026-05-31.

External Resources¶

For further information consult authority guidelines at the British Standards Institution (BSI).