# Introduction

## Introduction

The mailbox (í. Pósthólfið) is a closed area on Ísland.is. It contains and stores documents from the public sector (Document providers) to individuals and companies. Individuals and companies with an Icelandic ID number have their own mailbox.

Communication between the mailbox and the document provider is through a REST API. Document providers register a reference to new documents for publication on Island.is (also referred as index or documentIndex). The documents themselves are stored by the document provider they originate from.\
Users can identify themselves on Island.is and see a list of documents which belong to them. If the user retrieves a document the mailbox retrieves the document from the document provider. In other words, the document is only retrieved on user request.

Document providers need to implement the [Skjalaveita API](/products/postholf/postholf-03-interface-skjalaveita.md) which the mailbox has access to. The service needs to be created according to the pre-defined interface. The mailbox will be able to make a homogeneous query on any document provider where the endpoint different for each document provider.

## Overview

![](/files/Fb0tnuFUU91EbcVXWTG6)

Access Tokens are issued by the same idP for Skjalatilkynning API and Skjalabirting API (i.e., same idP for both directions).


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# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://docs.devland.is/products/postholf/postholf-01-intro-and-overview.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.