Registered E‑mail API allows you to integrate sending registered e‑mails within your existing e‑mail flows. Registered e‑mails can be sent automatically and the status of each e‑mail can be monitored in real-time.

The recipients do not have to register themselves, log in or install specific software. They can retrieve or refuse the message and the attached documents from their own e‑mail environment, from any device at any time.

This API offers the following functionalities:

  • Create new users.
  • Send registered e-mails.

API specification

Test the API on SwaggerHub

Mock API on SwaggerHub

Base URL

Conceptual model

Conceptual model



iDIN is a service offered by banks, which allows consumers to identify themselves with their bank's secure and reliable login methods.


A hash code is calculated for all submitted attachments to secure the authenticity of the message.

Registered E‑mail announcement

After sending the registered e‑mail, an announcement is sent to the recipient. The recipient can accept or reject the registered e‑mail. After acceptance, the recipient will receive the registered e‑mail in their own e‑mail environment.

Registered E-mail status summary

The service tracks where your registered e‑mail is in the sending and receiving process. You can check the status of the registered e‑mail in 3 different ways:

  • Check the delivery e‑mail in your inbox.
  • Check the online dashboard.
  • Check through an XML interface (optional).

API workflow

API workflow


If you have security protocols set up, please contact Registered E‑mail for additional configuration of the environment.

For example:

  • DomainKeys Identified Mail (DKIM).
  • Domain-based Message Authentication Reporting & Conformance (DMARC).


  • Sends registered e‑mails via the API.
  • Speeds up the document signing process with the digital signature functionality.

Getting started

Make sure you've read What's in it for you for more info on how to register and start testing APIs.


The API follows the KPN Store API Authentication Standard to secure the API. It includes the use of OAuth 2.0 client_id and client_secret to receive an access token.

Go to the Authentication tab on top of this page to find out how to:

  • Authenticate to an API using cURL.
  • Authenticate to an API on Swaggerhub.
  • Import Open API Specifications (OAS), also called Swagger files into Postman.

Setting up your third-party account with Registered E-mail

To start e‑mailing with the Registered E‑mail API, you need to create a Registered E‑mail user account.

Use the API request POST /api/user/ to create a new user on the Registered E‑mail platform.

You need to create an user for every person in your organization that needs to send registered e‑mails You only need to provide an e‑mail address.

How to...

Create users

This endpoint creates a new user (with the role of user):

POST /api/user/ See on Swaggerhub

Send the e‑mail address of the new user in the request body:

^^Request body^^
  "email_address": "",

A successful response returns the user ID:

  "id": 154

The new user receives an e-mail from, asking to activate the Dashboard account.

Send registered e‑mails

Use this endpoint to send registered e‑mails:

POST /webservice/mailsender/send See on Swaggerhub

Send the following details in the request body:

^^Request body^^
  "message_body": "this is the e‑mail body",
  "sender_email": "",
  "sender_real_name": "Jane Doe",
  "subject": "this is the subject",
  "x-own-id": "id",
  "x-own-guid": "guid",
  "x-own-campaign": "campaign code",
  "recipient_email": "",
  "recipient_language": "en",
  "attachments": [
      "attachment": "BAse64E=",
      "attachment_name": "attachment.pdf",
      "attachment_type": "application/pdf"
Parameter Type Description
message_body string Content of the message.
sender_email string E‑mail address of the sender.
sender_real_name string Name of the sender.
subject string Subject line of the e‑mail.
x-own-id string User ID.
x-own-guid string Globally Unique Identifier (GUID).
x-own-campaign string Campaign code. Allows to filter sent-emails using this code, for example 1234. Optional.
recipient_email string E‑mail address of the recipient.
recipient_language string Language of the recipient.
attachment_name string Name of the e‑mail attachment.
attachment_type string Document type of the e‑mail attachment. Supports are all common document types.

A successful response returns the ticket token and the ticket URL.

  "ticket_token": "K.SF1m-w",
  "ticket_url": "",
  "message": "OK"
Parameter Type Description
ticket_token string This is the ticket token.
ticket_url string Ticket URL.
message string Success message.

Return codes

Code Description
200 Success.
201 Created.
202 Accepted.
302 Found. Link in location header.
400 Bad request.
401 Unauthorized.
403 Forbidden.
404 Not found.
405 Method not allowed.
412 Precondition failed.
429 Too many requests.
500 Internal server error.
502 Bad gateway.
503 Service unavailable.

HTTP response headers

The following tables display the standard response headers that are returned with each API response:

Standard response field name Description
sunset This field will be populated with the deprecation details. By default the value is n/a.
api-version Indicates the API version you have used.
quota-interval Used to specify an integer (for example, 1, 2, 5, 60, and so on) that will be paired with the quota-time-unit you specify (minute, hour, day, week, or month) to determine a time period during which the quota use is calculated.
For example, an interval of 24 with a quota-time-unit of hour means that the quota will be calculated over the course of 24 hours.
quota-limit Number of API calls an user can make within a given time period.
If this limit is exceeded, the user will be throttled and API requests will fail.
quota-reset-UTC All quota times are set to the Coordinated Universal Time (UTC) time zone.
quota-time-unit Used to specify the unit of time applicable to the quota.
For example, an interval of 24 with a quota-time-unit of hour means that the quota will be calculated over the course of 24 hours.
quota-used Number of API calls made within the quota.
strict-transport-security The HTTP Strict-Transport-Security (HSTS) response header lets a website tell browsers that it should only be accessed using HTTPS, instead of using HTTP. All present and future subdomains will be HTTPS for a maximum of 1 year and access is blocked to pages or sub domains that can only be served over HTTP including HSTS preload lists of web browsers.
Strict-Transport-Security: max-age=31536000; includeSubDomains; preload.
Access control field name Description
access-control-allow-credentials Tells browsers whether to expose the response to frontend JavaScript when the request's credentials mode (Request.credentials) is include.
When a request's credentials mode (Request.credentials) is include, browsers will only expose the response to frontend JavaScript if the Access-Control-Allow-Credentials value is true. Boolean.
access-control-allow-origin Indicates whether the response can be shared with requesting code from the given origin.
access-control-allow-headers Used in response to a pre-flight request which includes the Access-Control-Request-Headers to indicate which HTTP headers can be used during the actual request.
access-control-max-age Indicates how long the results of a pre-flight request (that is the information contained in the Access-Control-Allow-Methods and Access-Control-Allow-Headers headers) can be cached.
access-control-allow-methods Indicates which HTTP methods are allowed on a particular endpoint for cross-origin requests.
For example: GET, PUT, POST, DELETE.
content-length The Content-Length entity header indicates the size of the entity-body, in bytes, sent to the recipient.
content-type The Content-Type entity header the client what the content type of the returned content actually is.

Mopinion feedback