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Letterbox delivery – Do you regularly sell products on your online shop that are small enough to fit inside a letterbox? If so, then letterbox delivery is an ideal shipping option for both your e-commerce logistics strategy and your customers. When you use this delivery method, your customer can still receive their order the next day, but without having to be at home to receive it in person.

At Sendcloud, we want to make the shipping process as easy as possible. And that’s what letterbox delivery is all about. In this article, we’ll give you a complete overview of the letterbox delivery options in the UK at your disposal, along with how they work. Then you’ll be all set to make your shipping process even more efficient! In this article, we’ll cover: 

What is letterbox delivery and how much does it cost?

Letterbox delivery is a trackable shipping service for parcels small enough to fit inside the recipient’s letterbox. The most important thing to remember when using this form of shipping is that the parcels must not exceed the maximum dimensions, otherwise they risk being undelivered.

Royal Mail Large Letter service is the most common letterbox delivery option in the UK. It’s popular among e-commerce retailers who sell smaller merchandise. 

The maximum dimensions for a Royal Mail Large Letter are:

  • 35.3 cm (length) x 25 cm (width) x 2.5 cm (height) 
  • 750 g (weight)

For a next-day delivery, the cost of shipping a Royal Mail Large Letter currently starts as low as £3.30. The prices increase if you choose additional services, such as higher shipping insurance coverage, sign-for delivery or track and trace.

Say you want to ship a small item valued at £20 or less. Using Royal Mail Large Letter with track and trace, the price of shipping starts at around £4.

If we compare the price of Royal Mail’s Large Letter service with its parcel service (Small Parcel), you can already see how it can amount to big savings. Next-day delivery for a Small Parcel starts at £3.85 with Royal Mail. That’s already about 17% more expensive than using Large Letter service to send an item of the same size and value! The reason for the price difference is that the maximum dimensions for Small Parcel service are higher. 

Here’s a comparison of these two Royal Mail shipping options:

Royal Mail Large Letter Royal Mail Small Parcel

35.3 cm (length) x 25 cm (width) x 2.5 cm (height)


45 cm (length) x 35 cm (width) x 16 cm (height)


Max. 750 g


Max. 2 kg


Next-day, without tracking: £3.30

Next-day, with tracking: Around £4.00


Next-day, without tracking: £3.85

Next-day, with tracking: Around £5.50


* Based on a stated value of £20 for the merchandise being shipped.

What letterbox delivery options are available in the UK?

As the comparison above shows, letterbox delivery with Royal Mail is an affordable shipping option for smaller items. But Royal Mail is not the only carrier who offers a letterbox deliver option. Hermes Postable is another option to consider for letterbox delivery in the UK.

One advantage of Hermes Postable is that you can send slightly larger parcels than with Royal Mail, although they must still be small enough to fit into a letterbox. The maximum dimensions allowed are 23 cm x 35 cm x 3 cm and up to 1 kg in weight. But for the extra size, you pay a bit more to ship with Hermes Postable: Next-day shipping starts at £4.76.

Royal Mail and Hermes Postable are the leading options for letterbox delivery. Other carriers such as UPS, DHL and DPD currently do not offer a designated letterbox service, as their deliveries generally need to be signed for or accepted in person by the recipient.

How do I ship a package using letterbox delivery?

It’s easy to send items using letterbox delivery. As with any type of shipping, it’s important to package your items securely to ensure they are not damaged during transit.

With letterbox delivery, the size of the package is very important. Remember to stick to the size and weight limits. Use sturdy, tear-resistant cardboard or padded envelopes to keep your items safe while also ensuring that they will fit easily into the customer’s letterbox. If your item needs additional cushioning, use foam paper or another thin packing material to keep the package from becoming too bulky.

Also remember that your carrier’s shipping restrictions still apply. For example, both Royal Mail and Hermes prohibit shipping of explosives and volatile substances, such as varnishes and some cosmetics. Hermes prohibits shipping of batteries, including lithium-ion batteries, as well as perfumes. Be sure to check your carrier’s restrictions if you are uncertain whether your items are suitable for posting.

letterbox delivery

The advantages of letterbox delivery

If you’re regularly shipping small items within the UK that fit inside a letterbox, then letterbox delivery is a great shipping option to offer your customers.

Using a service like Royal Mail Large Letter or Hermes Postable is a great way to keep these smaller items safe upon delivery, without unnecessary expenses. With track & trace letterbox delivery, your customers have the benefit of being able to track the shipment, without the hassle of having to be at home to receive it when it arrives.

This is an ideal shipping solution for sending small, relatively flat items such as t-shirts, books, DVDs or small gifts. Another advantage is that you can ship these items to a post office box, which is something that most other types of parcel delivery do not allow.

You’ll also find that letterbox delivery is a more sustainable, environmentally friendly option. Instead of filling a large cardboard box with plastic bubble wrap or foam packing peanuts just to send a small item, you can simply slip suitable small items inside an envelope with minimal extra packaging.

Why use letterbox delivery instead of parcel delivery?

You might be asking yourself: why would I send an item using letterbox delivery instead of regular parcel shipping? There are two main differences:

First, since a letterbox delivery fits conveniently into the customer’s letterbox, no one needs to be at home to receive the item. This is not only convenient for your customer; it also virtually eliminates the risk of the item being returned because of failure to deliver.

The second major difference is that letterbox delivery is generally much cheaper than regular parcel service. And lower shipping costs are something that any e-commerce retailer can be happy about.  

What happens if I post a parcel that is too big?

It’s important to stick to the strict size limits when using letterbox delivery. For one thing, if your parcel exceeds the size limits, you (or your customer) will be charged retroactively for the difference. But, even worse, the package may fail to be delivered if it is too large to fit inside the customer’s letterbox. Luckily, you can purchase templates that fit the size dimensions so you can test your packages before sending. 

In case Royal Mail or Hermes are unable to carry out a letterbox delivery, they will leave a notification in the recipient’s letterbox, instructing them to pick up the item at a nearby collection point.

Since the advantage of letterbox delivery is hassle-free shipment, it’s important to stick to the size limits, so you avoid any delivery issues in the first place. Otherwise, your customer may get stuck having to pick up a package or pay extra shipping. And they may think twice before ordering from your shop in the future.

Bottom line: The more delivery options, the more conversion

At Sendcloud, we like to offer you as many shipping options as possible, because we know better than anyone that multiple shipping options is a great way to boost conversion. With Sendcloud, you can mix ‘n’ match the best shipping methods from different carriers to create the perfect customized logistics strategy. Make sure to sign-up and try it out for free!

If your customer has a strong preference for a certain shipping option, but you don’t offer it, then there’s a good chance they’ll turn to one of your competitors.

So, remember to include letterbox delivery as one of your delivery options during checkout. Any questions? Please leave a comment or get in touch with our customer support!

Be sure to also check out our other articles on e-commerce logistics, such as our guides postage labels or label printers.


  • RILLA says:

    Just one problem….a letterbox doesn’t give you a proof of postage receipt. And for items that go missing and have to be refunded, proof of postage is vital for making a claim.

    • Stephanie Butcher says:

      Hi Rilla, this is a very good point. Therefore it’s definitely good to compare the pros and cons, and the costs saved with potential risks before choosing any shipping method you use, including Letterbox delivery.

    • zaeem ali says:

      That question also came to my mind, but Stephanie Butcher answered it, so I understand.

  • courier tracking says:

    ok nice