Editing Letter box (section)

===Europe===
{{More citations needed section|date=May 2017}}
The [[European standard]] for letter boxes, EN 13724:2002 "Postal services – Apertures of private letter boxes and letter plates – Requirements and test methods", replaces earlier national standards such as [[British Standard|BS]] 2911:1974 "Specification for letter plates" or [[DIN]] 32617. It specifies among other things:

* [[Envelope size]] C4 (229&nbsp;mm × 324&nbsp;mm) must be deliverable without bending or damage
* The internal volume must able to hold at least a 40&nbsp;mm high bundle of C4 envelopes
* [[wikt:aperture|Aperture]] width of either 230–280&nbsp;mm (> C4 width) or 325–400&nbsp;mm (> C4 height)
* Aperture height of 30–35&nbsp;mm
* Mounting height of between 0.7 and 1.7 m for the aperture
* When positioned externally, the post box should not allow more than 1% total capacity water ingress from natural precipitation or moisture causes.
* Various privacy, theft-protection, vandalism resistance and corrosion-resistance test requirements

This standard is voluntary. It was developed by a German mail boxes manufacturer Burg Wächter.