# Environmentally hazardous substances · Royal Mail / Post Office — Mailing and air-carriage restrictions by item category

For Environmentally hazardous substances · Royal Mail / Post Office, item category is Environmentally hazardous substances; carrier is Royal Mail / Post Office; restriction type is restricted; scope is UK only (international mail prohibited); conditions is Samples must not exceed 5litres/5kgs Pack in a leak-proof or sift-proof inner and protect by cushioning material in rigid outer packaging, recorded from its source on 2026-08-30.

- **Item category:** Environmentally hazardous substances _(verified: appears in the quote below)_
- **Carrier:** Royal Mail / Post Office _(our reading, not quoted from the source)_
- **Restriction type:** restricted _(our reading, not quoted from the source)_
- **Scope:** UK only (international mail prohibited) _(our reading, not quoted from the source)_
- **Conditions:** Samples must not exceed 5litres/5kgs Pack in a leak-proof or sift-proof inner and protect by cushioning material in rigid outer packaging _(verified: appears in the quote below)_

## What the source says

> Environmentally hazardous substances International – not allowed in the mail UK – allowed in the mail, see restrictions and packaging guidelines below: Samples must not exceed 5litres/5kgs Pack in a leak-proof or sift-proof inner and protect by cushioning material in rigid outer packaging

## Source

- https://www.postoffice.co.uk/mail/what-can-i-send

Last verified: 2026-08-30. Review by: 2027-08-30.
Part of [Mailing and air-carriage restrictions by item category](https://referencesource.org/shipping-restrictions-by-class/).