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Add email capabilities to .NET apps using Microsoft Graph

In this article, you extend the application you created in Build .NET apps with Microsoft Graph with Microsoft Graph mail APIs. You use Microsoft Graph to list the user's inbox and send an email.

List user's inbox

Start by listing messages in the user's email inbox.

  1. Open ./GraphHelper.cs and add the following function to the GraphHelper class.

    public static Task<MessageCollectionResponse?> GetInboxAsync()
{
    // Ensure client isn't null
    _ = _userClient ??
        throw new System.NullReferenceException("Graph has not been initialized for user auth");

    return _userClient.Me
        // Only messages from Inbox folder
        .MailFolders["Inbox"]
        .Messages
        .GetAsync((config) =>
        {
            // Only request specific properties
            config.QueryParameters.Select = new[] { "from", "isRead", "receivedDateTime", "subject" };
            // Get at most 25 results
            config.QueryParameters.Top = 25;
            // Sort by received time, newest first
            config.QueryParameters.Orderby = new[] { "receivedDateTime DESC" };
        });
}

  2. Replace the empty ListInboxAsync function in Program.cs with the following.

    async Task ListInboxAsync()
{
    try
    {
        var messagePage = await GraphHelper.GetInboxAsync();

        if (messagePage?.Value == null)
        {
            Console.WriteLine("No results returned.");
            return;
        }

        // Output each message's details
        foreach (var message in messagePage.Value)
        {
            Console.WriteLine($"Message: {message.Subject ?? "NO SUBJECT"}");
            Console.WriteLine($"  From: {message.From?.EmailAddress?.Name}");
            Console.WriteLine($"  Status: {(message.IsRead!.Value ? "Read" : "Unread")}");
            Console.WriteLine($"  Received: {message.ReceivedDateTime?.ToLocalTime().ToString()}");
        }

        // If NextPageRequest is not null, there are more messages
        // available on the server
        // Access the next page like:
        // var nextPageRequest = new MessagesRequestBuilder(messagePage.OdataNextLink, _userClient.RequestAdapter);
        // var nextPage = await nextPageRequest.GetAsync();
        var moreAvailable = !string.IsNullOrEmpty(messagePage.OdataNextLink);

        Console.WriteLine($"\nMore messages available? {moreAvailable}");
    }
    catch (Exception ex)
    {
        Console.WriteLine($"Error getting user's inbox: {ex.Message}");
    }
}

  3. Run the app, sign in, and choose option 2 to list your inbox.

    Please choose one of the following options:
0. Exit
1. Display access token
2. List my inbox
3. Send mail
4. Make a Graph call
2
Message: Updates from Ask HR and other communities
  From: Contoso Demo on Yammer
  Status: Read
  Received: 12/30/2021 4:54:54 AM -05:00
Message: Employee Initiative Thoughts
  From: Patti Fernandez
  Status: Read
  Received: 12/28/2021 5:01:10 PM -05:00
Message: Voice Mail (11 seconds)
  From: Alex Wilber
  Status: Unread
  Received: 12/28/2021 5:00:46 PM -05:00
Message: Our Spring Blog Update
  From: Alex Wilber
  Status: Unread
  Received: 12/28/2021 4:49:46 PM -05:00
Message: Atlanta Flight Reservation
  From: Alex Wilber
  Status: Unread
  Received: 12/28/2021 4:35:42 PM -05:00
Message: Atlanta Trip Itinerary - down time
  From: Alex Wilber
  Status: Unread
  Received: 12/28/2021 4:22:04 PM -05:00

...

More messages available? True

GetInboxAsync explained

Consider the code in the GetInboxAsync function.

Accessing well-known mail folders

The function uses the _userClient.Me.MailFolders["Inbox"].Messages request builder, which builds a request to the List messages API. Because it includes the MailFolders["Inbox"] request builder, the API only returns messages in the requested mail folder. In this case, because the inbox is a default, well-known folder inside a user's mailbox, it's accessible via its well-known name. Nondefault folders are accessed the same way, by replacing the well-known name with the mail folder's ID property. For details on the available well-known folder names, see mailFolder resource type.

Accessing a collection

Unlike the GetUserAsync function from the previous section, which returns a single object, this method returns a collection of messages. Most APIs in Microsoft Graph that return a collection don't return all available results in a single response. Instead, they use paging to return a portion of the results while providing a method for clients to request the next page.

Default page sizes

APIs that use paging implement a default page size. For messages, the default value is 10. Clients can request more (or less) by using the $top query parameter. In GetInboxAsync, adding $top is accomplished with the .Top(25) method.

Note

The value passed to .Top() is an upper-bound, not an explicit number. The API returns a number of messages up to the specified value.

Getting subsequent pages

If there are more results available on the server, collection responses include an @odata.nextLink property with an API URL to access the next page. The .NET client library provides the NextPageRequest property on collection page objects. If this property is non-null, there are more results available.

The NextPageRequest property exposes a GetAsync method which returns the next page.

Sorting collections

The function uses the OrderBy method on the request to request results sorted by the time the message is received (ReceivedDateTime property). It includes the DESC keyword so that messages received more recently are listed first. This method adds the $orderby query parameter to the API call.

Send mail

Now add the ability to send an email message as the authenticated user.

  1. Open ./GraphHelper.cs and add the following function to the GraphHelper class.

    public static async Task SendMailAsync(string subject, string body, string recipient)
{
    // Ensure client isn't null
    _ = _userClient ??
        throw new System.NullReferenceException("Graph has not been initialized for user auth");

    // Create a new message
    var message = new Message
    {
        Subject = subject,
        Body = new ItemBody
        {
            Content = body,
            ContentType = BodyType.Text
        },
        ToRecipients = new List<Recipient>
        {
            new Recipient
            {
                EmailAddress = new EmailAddress
                {
                    Address = recipient
                }
            }
        }
    };

    // Send the message
    await _userClient.Me
        .SendMail
        .PostAsync(new SendMailPostRequestBody
        {
            Message = message
        });
}

  2. Replace the empty SendMailAsync function in Program.cs with the following.

    async Task SendMailAsync()
{
    try
    {
        // Send mail to the signed-in user
        // Get the user for their email address
        var user = await GraphHelper.GetUserAsync();

        var userEmail = user?.Mail ?? user?.UserPrincipalName;

        if (string.IsNullOrEmpty(userEmail))
        {
            Console.WriteLine("Couldn't get your email address, canceling...");
            return;
        }

        await GraphHelper.SendMailAsync("Testing Microsoft Graph",
            "Hello world!", userEmail);

        Console.WriteLine("Mail sent.");
    }
    catch (Exception ex)
    {
        Console.WriteLine($"Error sending mail: {ex.Message}");
    }
}

  3. Run the app, sign in, and choose option 3 to send an email to yourself.

    Please choose one of the following options:
0. Exit
1. Display access token
2. List my inbox
3. Send mail
4. Make a Graph call
3
Mail sent.

    Note

    If you're testing with a developer tenant from the Microsoft 365 Developer Program, the email you send might not be delivered, and you might receive a nondelivery report. If you want to unblock sending mail from your tenant, contact support via the Microsoft 365 admin center.

  4. To verify the message was received, choose option 2 to list your inbox.

SendMailAsync explained

Consider the code in the SendMailAsync function.

Sending mail

The function uses the _userClient.Me.SendMail request builder, which builds a request to the Send mail API. The request builder takes a Message object representing the message to send.

Creating objects

Unlike the previous calls to Microsoft Graph that only read data, this call creates data. To create items with the client library, you create an instance of the class representing the data (in this case, Microsoft.Graph.Message) using the new keyword, set the desired properties, then send it in the API call. Because the call is sending data, the PostAsync method is used instead of GetAsync.

Next step

Add additional Microsoft Graph APIs