How can I send mail in office 365 REST API?

Question

I've found the following documentation on how to send email using Office 365 rest API.

This is the example given on the doucmentation:

POST https://outlook.office.com/api/v2.0/me/sendmail

{
  "Message": {
    "Subject": "Meet for lunch?",
    "Body": {
      "ContentType": "Text",
      "Content": "The new cafeteria is open."
    },
    "ToRecipients": [
      {
        "EmailAddress": {
          "Address": "[email protected]"
        }
      }
    ],
    "Attachments": [
      {
        "@odata.type": "#Microsoft.OutlookServices.FileAttachment",
        "Name": "menu.txt",
        "ContentBytes": "bWFjIGFuZCBjaGVlc2UgdG9kYXk="
      }
    ]
  },
  "SaveToSentItems": "false"
}

This works fine if the user authorizes the application to act on it's behalf. However, I am using client crednetial to build a daemon application that acts on behalf of all users in the given tenant hence "POST https://outlook.office.com/api/v2.0/me/sendmail" couldn't work because its is referencing the "me" and can't tell which user is sending the email.

I would appericiate if you can help with sample example. FYI: I am using Java but your answer doesn't have to be in Java.

Answer 1

Replace the /me bit of the URL with /users/<userid>. You can not use /me for any API call with a token from client credentials.