MSDN Documentation

Outlook Add-ins: Authentication Tutorials

This section provides detailed guidance and practical examples on implementing authentication for your Outlook add-ins. Securely authenticating users is crucial for protecting sensitive data and providing a personalized experience.

Understanding Authentication Flows

Outlook add-ins can leverage various authentication protocols, primarily OAuth 2.0, to allow users to sign in to your service without sharing their credentials directly with the add-in. We'll cover common scenarios such as:

• OAuth 2.0 Authorization Code Grant Flow
• OAuth 2.0 Implicit Grant Flow (for client-side only scenarios)
• Using Microsoft Identity Platform for Office 365 authentication

Tutorial 1: Implementing OAuth 2.0 with a Custom Backend

Learn how to set up an OAuth 2.0 flow between your Outlook add-in and your own backend authentication service. This tutorial walks you through:

• Registering your application with an identity provider.
• Handling authorization requests and redirects.
• Exchanging authorization codes for access tokens.
• Securely storing and using tokens.

Example Scenario: Authenticating users against a custom CRM.

// Example snippet: Initiating OAuth flow
                function startAuthFlow() {
                    const clientId = 'YOUR_CLIENT_ID';
                    const redirectUri = encodeURIComponent('YOUR_REDIRECT_URI');
                    const scope = encodeURIComponent('read write offline_access'); // Scopes your add-in needs
                    const authUrl = `https://YOUR_AUTH_SERVER/authorize?response_type=code&client_id=${clientId}&redirect_uri=${redirectUri}&scope=${scope}&state=some_random_string`;

                    Office.context.ui.openPopup(authUrl, { width: 400, height: 600 });
                }

Tutorial 2: Leveraging Microsoft Identity Platform

For add-ins that integrate with Microsoft services or require users to sign in with their Microsoft 365 accounts, the Microsoft Identity Platform is the recommended approach. This tutorial covers:

• Registering your add-in in Azure Active Directory (now Microsoft Entra ID).
• Using the Microsoft Authentication Library (MSAL) for JavaScript.
• Acquiring tokens for Microsoft Graph API.
• Handling single sign-on (SSO) for a seamless user experience.

Key Concepts: Application permissions vs. Delegated permissions, token caching.

// Example snippet: Acquiring token using MSAL.js
                const msalConfig = {
                    auth: {
                        clientId: 'YOUR_AZURE_CLIENT_ID',
                        authority: 'https://login.microsoftonline.com/common'
                    }
                };
                const msalInstance = new msal.PublicClientApplication(msalConfig);

                async function getTokenForMicrosoftGraph() {
                    const request = {
                        scopes: ["User.Read", "Mail.Read"]
                    };
                    try {
                        const silentResult = await msalInstance.acquireTokenSilent(request);
                        return silentResult.accessToken;
                    } catch (error) {
                        console.log("Silent token acquisition failed. Trying interactive.");
                        const interactiveResult = await msalInstance.acquireTokenPopup(request);
                        return interactiveResult.accessToken;
                    }
                }

Next Steps

Once you have a solid understanding of authentication, explore how to work with data in Outlook or learn about deploying your authenticated add-in.