Facing issue while sending mail using Microsoft Graph API With Attachment in c#

Question

I am trying to send mail using Microsoft Graph API With Attachment as per this article where I have explained the issue with error code 400 - https://stackoverflow.com/questions/77825549/facing-issue-while-sending-mail-using-microsoft-graph-api-with-attachment-in-c-s Can some one suggest here what I am missing? Thanks

Answer 1

Hi @Sandeep K, It seems that you're not using Graph's SDK, it is recommended that you use GraphClient to send requests. Like the code below:

var scopes = new[] { "https://graph.microsoft.com/.default" };

// Values from app registration
var clientId = "Your ClienId";
var tenantId = "Your TenantId";
var clientSecret = "Your Clent Secret";

var file = "Your Path\\MailWork.txt";
byte[] fileArray = System.IO.File.ReadAllBytes(@file);

// using Azure.Identity;
var options = new ClientSecretCredentialOptions
{
    AuthorityHost = AzureAuthorityHosts.AzurePublicCloud,
};

// https://learn.microsoft.com/dotnet/api/azure.identity.clientsecretcredential
var clientSecretCredential = new ClientSecretCredential(
    tenantId, clientId, clientSecret, options);

var graphClient = new GraphServiceClient(clientSecretCredential, scopes);


var requestBody = new SendMailPostRequestBody
{
    Message = new Message
    {
        Subject = "Meet for lunch?",
        Body = new ItemBody
        {
            ContentType = BodyType.Text,
            Content = "The new cafeteria is open.",
        },
        ToRecipients = new List<Recipient>
        {
            new Recipient
            {
                EmailAddress = new EmailAddress
                {
                    Address = "******@contoso.onmicrosoft.com",
                },
            },
        },
        Attachments = new List<Attachment>
        {
            new FileAttachment
            {
                OdataType = "#microsoft.graph.fileAttachment",
                Name = "attachment.txt",
                ContentType = "text/plain",
                ContentBytes = fileArray,
            },
        },
    },
};

// To initialize your graphClient, see https://learn.microsoft.com/en-us/graph/sdks/create-client?from=snippets&tabs=csharp
await graphClient.Users["<userEmail>"].SendMail.PostAsync(requestBody);

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