/message/sendTransactional

Sends a prepared message as a transactional message.
Attachments can be encoded using base64encode.org
Request body example:

{
"parameters":
  [{"name" : "Parameter Name 1","value" : "Parameter Value 1"},
   {"name" : "Parameter Name 2","value": "Parameter Value 2"}],
    "attachments":
    [{"name" : "twitter_logo.png",
      "contentType" : "image/png",
      "content": "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"}]
}