Send Emails via Microsoft Graph in C#

Send Emails using C# and Microsoft Graph API

Integrating Microsoft Graph with the Aspose.Email for .NET library allows developers to streamline email sending through Microsoft 365 services, bringing enhanced functionality such as attachment handling, message tracking, and secure communication. This API integration simplifies the creation and delivery of personalized, high-performance email communications directly from your .NET applications.

Microsoft Graph Email Sending: How It Works

Microsoft Graph is a RESTful web API that enables access to Microsoft 365 services, including the ability to send emails. When sending emails via Microsoft Graph, requests are sent using HTTP POST to the /sendMail endpoint, along with the message payload. This payload is typically a JSON object that contains the email content (recipients, subject, body, etc.) and any attached files.

Upon receiving the request, Microsoft Graph processes it and responds with an HTTP status code. A successful email send operation returns a 202 Accepted response, indicating the message has been queued for delivery. Handling these responses allows developers to ensure successful communication or debug any issues that may arise.

Authenticating Microsoft Graph Requests

Calling Microsoft Graph isn’t as simple as sending an HTTP request—you first need to handle authentication. Microsoft Graph is protected by Azure Active Directory (Azure AD), which means you must obtain an access token before making any request. This access token specifies what operations you’re allowed to perform, based on permissions granted during the authentication process.

To authenticate, you first need to set up an app registration in Azure AD, define the required permissions, and then request an access token using the appropriate OAuth flow. Once you have the token, include it in the Authorization header of your requests.

Aspose.Email for .NET simplifies the process of obtaining and managing the access token, ensuring that the application can securely interact with Microsoft Graph. By implementing its ITokenProvider interface, developers can efficiently retrieve the OAuth 2.0 token required for authentication. After setting up an app registration in the Azure portal and granting the necessary permissions like Mail.Send, developers can use Aspose.Email to incorporate extensive email functionalities into their applications.

Streamlining your email communication starts with a few essential steps:

1. Register your application in the Azure portal and grant permissions such as Mail.Send for sending emails.
2. Obtain an Access Token: Implement the ITokenProvider interface of the Aspose.Email for .NET to retrieve the OAuth 2.0 token required for authentication.
3. Install Aspose.Email for .NET via NuGet or by downloading its DLL file.

By following these steps you’ll be well-equipped to start coding.

Understanding Microsoft Graph Request and Response

Request: The email data, including subject, body, recipient details, and attachments, is structured in a JSON format. When the Send method is called, this data is serialized and sent as a POST request to the Microsoft Graph /sendMail endpoint.

Response: The response from the Microsoft Graph API is returned as a status code. A 202 Accepted response indicates successful transmission, while error codes such as 401 Unauthorized or 403 Forbidden may suggest issues with authentication or permissions.

In Aspose.Email, the library provides built-in features for forming, sending requests, and parsing responses when interacting with external services like Microsoft Graph. These functionalities allow developers to streamline communication with Microsoft 365 services (e.g., Outlook, Calendar, Contacts) without needing to manually craft HTTP requests or parse raw JSON responses.

1. Forming Requests:
   Aspose.Email simplifies the creation of requests by providing specific classes and methods that abstract the complexity of request formation. For instance, developers can interact with emails, calendars, and contacts through intuitive APIs without manually building the required Microsoft Graph requests.

2. Sending Requests:
   The library includes built-in mechanisms to send requests directly to services like Microsoft Graph. Instead of dealing with authentication and HTTP methods manually, Aspose.Email handles the process behind the scenes. This includes adding necessary headers like authorization tokens and content types, ensuring the request is properly formatted for successful communication with Microsoft services.

3. Parsing Responses:
   Aspose.Email also supports response parsing, converting raw JSON or XML responses into structured objects, such as MailMessage, CalendarEvent, or Contact. This eliminates the need for developers to handle JSON parsing directly. The parsed data can be used immediately within the application, making the integration process more seamless and efficient.

These features allow developers to focus more on business logic rather than managing the underlying complexities of interacting with services like Microsoft Graph.

C# Code Example for Sending Emails via Microsoft Graph

The following C# code will help you effortlessly create, customize, and dispatch email messages using GraphClient provided by Aspose.Email API. With a few simple lines of code it allows you to:

1. Create an instance of IGraphClient by calling GetClient method.
2. Initialize an eml object of MailMessage class, set its properties.
3. Send the message using the Send method of the library.

using Aspose.Email;
using Aspose.Email.Clients.Graph;

// Generate the access token
AccessTokenProvider tokenProvider = new AccessTokenProvider();

// Create a Graph client
IGraphClient client = GraphClient.GetClient(tokenProvider, "tenant ID");

// Create a new message
var eml = new MailMessage(fromAddress, toAddress, subject, body);
   
// Send message
client.Send(eml);

Send Emails with Attachments

Sending emails with attachments through Microsoft Graph is simple and efficient with the Aspose.Email for .NET library. Attachments can be any file type, such as documents, images, or PDFs, which are sent alongside the email message. This is particularly useful for sharing resources like reports, presentations, or other vital documents directly through your .NET application.

In the following code snippet, attachments are added to the MailMessage object before the email is sent:

// Add attachments to the message
Attachment attachment = new Attachment("path_to_attachment");
eml.Attachments.Add(attachment);

How Attachments Are Processed

1. Loading Attachments: The attachment is loaded from the file path specified (“path_to_attachment”), which could be a local file or a stream. The Attachment class allows you to add any file type as an attachment, making it highly flexible.
2. Adding to the Email: Once the attachment is created, it is added to the email message using the Attachments.Add() method. This method appends the file to the MailMessage object’s attachment collection, which is automatically included when the message is sent via Microsoft Graph.
3. Sending the Email: Once the attachments have been added to the message, the Send method from the IGraphClient interface sends the email with all attached files.

Handling Multiple Attachments

You can easily add multiple attachments by repeating the process for each file. Here’s how to attach more than one file:

Attachment attachment1 = new Attachment("file1.pdf");
Attachment attachment2 = new Attachment("image.png");
eml.Attachments.Add(attachment1);
eml.Attachments.Add(attachment2);

Attachment Size Limits

It’s important to note that Microsoft Graph enforces size limits for email messages. The total size of an email, including attachments, must not exceed 25 MB. If you need to send larger files, consider uploading them to a cloud storage service (like OneDrive) and sending the file link instead.

C# API for Email Manipulation: Features and Installation

The C# library offers a robust set of features designed to empower developers with comprehensive email processing capabilities including message parsing and extraction, conversion between various formats, attachment management, signatures and encryption, calendar and event management, address validation, search and filtering and more. It empowers developers with a versatile toolkit to seamlessly manage and manipulate email communication within their applications, providing a streamlined and efficient user experience.

Additional Features of Aspose.Email for .NET

Beyond sending emails, Aspose.Email for .NET offers a wide range of features for advanced email management:

• Attachment Management: Add, extract, or manipulate attachments within email messages.
• Message Parsing and Formatting: Convert between different email formats (MSG, EML, MHTML, etc.) and parse the content of email messages.
• Email Signatures and Encryption: Sign and encrypt emails to ensure secure communication.
• Calendar Integration: Manage and send calendar events through the API, enhancing overall communication workflows.

By leveraging these features, developers can build rich, scalable email applications tailored to their specific needs.

Install the .NET API

Before you start, spare a minute to install the library into your project. You can do this by any of the most convenient ways for you:

• using NuGet Package Manager
• referencing the required assemblies
• or simply by using the following command within the Package Manager Console in Visual Studio:

PM> Install-Package Aspose.Email