The V4 Email Delivery API will introduce several new features to the platform. Methods included in the new Email Delivery RESTful API will be introduced over the next year and utilize a new hostname, response format, and a truly REST-compliant means of authentication.
Note: Not all of the Email Delivery API’s methods have been ported to the new API. Reference our prior version of the Email Delivery API for a list of older methods.

Host Name

All API method invocations will go through a new hostname. This hostname is


All public, private, or internal invocations of the new API must include authorization. In the new API, authorization utilizes the Authorization header. Each request will continue to require current API keys, but it should be sent in through the header as shown below:

Authorization:  apikey=XXXXXXXX

The REST API is accessed via the URL in this format:[PARAMS]

METHOD-NAME[PARAMS] is the URI of the API method you wish to use. For GET requests, the [PARAMS] will use a query string for the parameters. For POST requests, the [PARAMS] will use post data for the parameters.

(You can initiate a secure connection by changing “http” to “https”.)

Response Format

Each invocation must have the Accept request header specified with one of the following valid values:

  • application/json
  • application/xml
  • text/html (NOTE: html is only useful for visualizing the data and should not be used for development purposes)


  • 200 – OK
    • The action was successful.
  • 202 – Duplicate query
    • A duplicate request query for the same exact information (i.e. exact same parameters) has been made while the first request is still processing. Results will be returned only to the first request.
  • 503 – Service Unavailable
    • The server is currently unavailable. It could be overloaded or down for maintenance, but this is just temporary. Try the request again in a short while.