Microsoft Graph API using uploadsession not able to recieve email with attachments

Question

Email Not been recieved with attachments when I try to use Uploadsession using Graph API. can someone help me uderstand why this is happening. I have not recieved any error.

      Message draft = await graphServiceClient.Users["UserID"].Messages.Request().AddAsync(email);
        //Message draft = graphServiceClient.Users["UserID"].Mailfolders.Drafts.Messages.Request().AddAsync(email);

        var stream = System.IO.File.Open(@"C:\attach\DYN28_6579332_33242556.csv", System.IO.FileMode.Open, FileAccess.Read, FileShare.None);
        var attachmentItem = new AttachmentItem
        {
            AttachmentType = AttachmentType.File,
            Name = "DYN28_6579332_33242556.csv",
            Size = stream.Length
        };
        var uploadSession = await graphServiceClient.Users["Userid"].Messages[draft.Id]
                                .Attachments
                                .CreateUploadSession(attachmentItem)
                                .Request()
                                .PostAsync();
        var maxSlicesize = 320 * 1024;
        var largeFileUploadTask = new LargeFileUploadTask<FileAttachment>(uploadSession, stream, maxSlicesize);
        IProgress<long> progress = new Progress<long>(prog => {
            Console.WriteLine($"Uploaded {prog} bytes of {stream.Length} bytes");
        });

            // Upload the file
            var uploadResult = await largeFileUploadTask.UploadAsync(progress);

            if (uploadResult.UploadSucceeded)
            {
            // The ItemResponse object in the result represents the
            // created item.
            //Console.WriteLine($"Upload complete, item ID: {uploadResult.ItemResponse.Id}");
            Console.WriteLine("upload completed");
            }

  Finally sending email with 
                                                                      
                                                                         
  await graphServiceClient.Users["userid"].Messages[draft.Id]
                                  .Send()
                                  .Request()
                                  .PostAsync();

They have a limit of ~3MB use S3 download link if you have it. — yodellingbutters
As a workaround, you can use SMTP for sending the mail, which doesn't have this restriction. — yodellingbutters
We have recently migrated to graph API..earlier we used to have SMTP which doesn't have any restrictions.What is S3 download link? — User123
Can you please give me code on how to zip the attachments and send it through email using graph API — User123

Neel Shah Neel Shah · Accepted Answer · 2021-03-04T03:06:39

There is a limit of 4MB on a single request in the Graph API. To send larger attachments, you need to first create an upload session against the email message/calendar event, and upload your attachment in a number of requests as part of this session. AFAIK each of the smaller POST requests would also need to stay below the 4MB limit.

You can find more detailed documentation and a sample walkthrough here.

POST https://graph.microsoft.com/v1.0/me/messages/AAMkADI5MAAIT3drCAAA=/attachments/createUploadSession
Content-type: application/json

{
  "AttachmentItem": {
    "attachmentType": "file",
    "name": "flower",
    "size": 3483322
  }
}

Microsoft Graph API using uploadsession not able to recieve email with attachments

1 Answers