title: How to retrieve contents of an itemAttachment via the Microsoft Graph API
body: <p>I'm currently developing a solution which is retrieving e-mails via the Microsoft Graph API. In november 2015 Microsoft stated it is ready for production and I've read in another forum post that if you start now on developing using a Microsoft API, you should use the Graph API, since it is the future.</p>
  
  <p>Everything is going well except for one thing and that is the following.</p>
  
  <p>I must retrieve e-mails. Inside these e-mails there are of course attachments. These attachments come in some variaties. fileAttachment (images, documents etc.), referenceAttachments  and itemAttachments (outlook-item). The issue here is with the itemAttachments. An itemAttachment can be anything from an appointment to another message. The problem here is that I'm not able to get and retrieve the contentBytes in some way which is working for fileAttachments. A related object to itemAttachment is outlookItem. There is also a page with a description made for this outlookItem, but the examples and the details are missing.
  The user rights are set to Mail.Read and Mail.ReadWrite.</p>
  
  <p>Links:
  General overview: <a href="http://graph.microsoft.io/docs/overview/overview" rel="noreferrer">http://graph.microsoft.io/docs/overview/overview</a>
  Get outlookItem (empty?):</p>
  
  <p>Example call and response I get. Please note the types of the attachments.
  <a href="https://graph.microsoft.com/v1.0" rel="noreferrer">https://graph.microsoft.com/v1.0</a> /users/ /messages/ /attachments</p>
  
  <pre><code>{
    "@odata.context": "link",
    "value": [
      {
        "@odata.type": "#microsoft.graph.fileAttachment",
        "id": "AAMkAGU2NmIwMTcxLTljYzUtNGRiMi1hZjczLTllNzhiZDRiNWZlZABGAAAAPAD_Lx_gimDGRqSr98J_O_e6BwDcWyYHlO7rS5_XpLHCx6NSAAIMC0V-AADcWyYHlO7rS5_XpLHCx6NSAAIMC6RgAAABEgAQAGhN_vm1RlBPt7V4N9a89UY=",
        "lastModifiedDateTime": "2016-01-13T14:25:33Z",
        "name": "image001.png",
        "contentType": "image/png",
        "size": 5077,
        "isInline": true,
        "contentId": "image001.png@01D14E16.A3A32480",
        "contentLocation": null,
        "contentBytes": "iVBORw0KGgoAAAANSUhEUgAAAKAAAACCCAIAAABOyVRHAAAAAXNSR0IArs4c6QAAEndJREFUeF7tXQ1QFFe2bkbU... (truncated)"
      },
      {
        "@odata.type": "#microsoft.graph.fileAttachment",
        "id": "AAMkAGU2NmIwMTcxLTljYzUtNGRiMi1hZjczLTllNzhiZDRiNWZlZABGAAAAPAD_Lx_gimDGRqSr98J_O_e6BwDcWyYHlO7rS5_XpLHCx6NSAAIMC0V-AADcWyYHlO7rS5_XpLHCx6NSAAIMC6RgAAABEgAQAFnSLgIC5wZOosmLtBWK8gE=",
        "lastModifiedDateTime": "2016-01-13T14:25:34Z",
        "name": "image002.png",
        "contentType": "image/png",
        "size": 3722,
        "isInline": true,
        "contentId": "image002.png@01D14E16.A3A32480",
        "contentLocation": null,
        "contentBytes": "iVBORw0KGgoAAAANSUhEUgAAAPoAAABSCAYAAAB9o8m+AAAAGXRFWHRTb... (truncated)"
      },
      {
        "@odata.type": "#microsoft.graph.fileAttachment",
        "id": "AAMkAGU2NmIwMTcxLTljYzUtNGRiMi1hZjczLTllNzhiZDRiNWZlZABGAAAAPAD_Lx_gimDGRqSr98J_O_e6BwDcWyYHlO7rS5_XpLHCx6NSAAIMC0V-AADcWyYHlO7rS5_XpLHCx6NSAAIMC6RgAAABEgAQANOuw7m8sW1Ot3MivYQ5OYU=",
        "lastModifiedDateTime": "2016-01-13T14:25:24Z",
        "name": "Knipsel.PNG",
        "contentType": null,
        "size": 7641,
        "isInline": false,
        "contentId": null,
        "contentLocation": null,
        "contentBytes": "iVBORw0KGgoAAAANSUhEUgAAAKAAAACCCAYAAADBq8MQAAA... (truncated)"
      },
      {
        "@odata.type": "#microsoft.graph.itemAttachment",
        "id": "AAMkAGU2NmIwMTcxLTljYzUtNGRiMi1hZjczLTllNzhiZDRiNWZlZABGAAAAPAD_Lx_gimDGRqSr98J_O_e6BwDcWyYHlO7rS5_XpLHCx6NSAAIMC0V-AADcWyYHlO7rS5_XpLHCx6NSAAIMC6RgAAABEgAQAPEUC740tjtAlNTe8NpopUI=",
        "lastModifiedDateTime": "2016-01-14T15:55:07Z",
        "name": "RE: Test met plaatje",
        "contentType": null,
        "size": 36972,
        "isInline": false
      }
    ]
  }
  </code></pre>
  
  <p>I've tried to change the GET-statement by pasting the attachment id with or without the messages path and the expand feature (which is only supported one level deep), but I can't seem te find the solution.
  Something I've found is this question, which is kind of the same, however it is for the office365 unified API. <a href="https://stackoverflow.com/questions/32749496/how-to-retrieve-itemattachment-contents-from-office-365-rest-api">How to retrieve ItemAttachment contents from Office 365 REST API?</a>. </p>
  
  <p>So, the question: How can I retrieve the contents of an outlookItem via the Microsoft Graph API? And how do I know what to expect? Can anybody help me getting past this obstacle.</p>