Using Microsoft/Office 365 OAUTH + EWS and Ms Graph API

Microsoft Office365 EWS and Ms Graph API servers have been extended to support authorization via the industry-standard OAuth 2.0 protocol. Using OAUTH protocol, user can do authentication by Microsoft Web OAuth instead of inputting user and password directly in application. This way is more secure, but a little bit complex.

Create your application in Azure Portal

To use Microsoft/Office365 OAUTH in your application, you must create a application in https://portal.azure.com.

Sign in to the Azure portal using either a work or school account or a personal Microsoft account.
If your account gives you access to more than one tenant, select your account in the top right corner, and set your portal session to the Azure AD tenant that you want.
In the left-hand navigation pane, select the Azure Active Directory service, and then select App registrations > New registration.

Single tenant and multitenant in account type

When the register an application page appears, enter a meaningful application name and select the account type.

Select which accounts you would like your application to support.

If your application only supports the users in your directory or organization, please select Single tenant type;
If your application needs to support all users in Office 365 and Microsoft personal account (hotmail.com, outlook.com), please select Multitenant type, and you must verify publisher.

Because we want to support all Office 365 and LIVE SDK (hotmail, outlook personal account), so select Accounts in any organizational directory and personal Microsoft accounts.

API Permission

Now we need to add permission to the application:

Click API Permission -> Add a permission -> Microsoft Graph -> Delegated Permission -> User.Read, email, offline_access, openid, profile, SMTP.Send, IMAP.AccessAsUser.All and Mail.Send. POP.AccessAsUser.All.

EWS API permission

With the above permissions, your application can support SMTP, POP, IMAP and Graph API service. If your application needs to support EWS protocol either, add EWS permission like this:

Click API Permission -> Add a permission -> APIs in my organization uses -> Office 365 Exchange Online -> Delegated Permission -> Check EWS.AccessAsUser.All

Here is permissions list:

Authentication and redirect uri

Click "Authentication" -> Add a platform -> Mobile and desktop applications -> Redirect Uri, please check or add the following URI.
```
https://login.microsoftonline.com/common/oauth2/nativeclient
https://login.live.com/oauth20_desktop.srf
http://127.0.0.1
                
```
* "https://login.live.com/oauth20_desktop.srf" is used for Live SDK, "http://127.0.0.1" is used for local Http Listener.
If your application needs to support Microsoft personal account, set both "Live SDK Support" and "Treat application as a public client" to "Yes".
If your application is web application, you should use a page to get authorization code instead of HttpListener. You need to add your page path to Authentication -> add a platform -> web -> Redirect URIs in your Azure application.

Client Id and client secrets

Now we need to create a client secret for the application, click Certificates and secrets -> client secrets and add a new client secret.

After client secret is created, store the client secret value to somewhere, Please store client secret value by yourself, because it is hidden when you view it at next time.

Branding and verify publisher

Now we click Branding, you can edit your company logo, URL and application name. If your application supports multitenant (access user in all Office 365 and Microsoft personal account), you must complete the publisher verification.

It is not difficult, you can have a look at publisher verification. After publisher verification is completed, your branding is like this:

You must complete the publisher verification for multitenant application, otherwise, your application will not request access token correctly.

Client id and tenant

Now you can click Overview to find your client id and tenant.

If your application is single tenant, use the tenant value in tokenUri and authUri instead of "common". If your application is multitenant, use "common" as tenant.

Above client_id and secret support both "Office365 + SMTP/POP/IMAP/EWS" and "Live (hotmail, outlook personal account) + SMTP/POP/IMAP".

Use client id and client secret to request access token

You can use client id and client secret to get the user email address and access token like this:

Your application uses a web browser/browser control to open OAUTH URL;
User inputs user and password in Web Authentication, the server returns access token back to your application
Your application uses access token to access the server. You can find the example codes in EASendMail Installation Path\Samples_{Programming language/Developer Tool}\Oauth.* project.

Access token expiration and refresh token

You don’t have to open browser to request access token every time. By default, access token expiration time is 3600 seconds, you can use the access token repeatedly before it is expired. After it is expired, you can use refresh token to refresh access token directly without opening browser. You can find full sample project in EASendMail installation path to learn how to refresh token.

You should create your client id and client secret, don't use the client id in the sample project, it is only for test purpose. If you got "This app isn't verified" information, please click "advanced" -> Go to ... for test.

Request access token

[C# - Get access token and user with Microsoft.Identity.Client]
// You can install Microsoft.Identity.Client by NuGet
// Install-Package Microsoft.Identity.Client

using Microsoft.Identity.Client;

var pcaOptions = new PublicClientApplicationOptions
{
    ClientId = "your client id",
    TenantId = "common",
    RedirectUri = "https://login.microsoftonline.com/common/oauth2/nativeclient"
};

var pca = PublicClientApplicationBuilder
    .CreateWithApplicationOptions(pcaOptions)
    .WithLogging(MyLoggingMethod, LogLevel.Info,
           enablePiiLogging: true,
           enableDefaultPlatformLogging: true).
    Build();

var ewsScopes = new string[] { "https://outlook.office.com/EWS.AccessAsUser.All"};
// var ewsScopes = new string[] { "https://graph.microsoft.com/Mail.Send"}; // Ms Graph API scope

// Make the interactive token request
var authResult = await pca.AcquireTokenInteractive(ewsScopes).ExecuteAsync();

// then you can get access token and user from the following properties
// authResult.AccessToken;
// authResult.Account.Username;

Use access token to send email with Office 365 EWS protocol

After you get user email address and access token, you can use the following codes to send email using Office365 EWS protocol.

Example

[Visual Basic, C#, C++] To get the full samples of EASendMail, please refer to Samples section.

[VB - Send Email using Office 365 OAUTH Authentication]
    
Imports EASendMail

Sub SendMailWithXOAUTH2(userEmail As String, accessToken As String)

    Try
    ' set Office365 EWS server address
        Dim oServer As SmtpServer = New SmtpServer("outlook.office365.com")

    ' set Office365 Ms Graph API server address
    ' Dim oServer As SmtpServer = New SmtpServer("https://graph.microsoft.com/v1.0/me/sendMail")

    ' set Exchange Web Service protocol (EWS) -Office 365 
    oServer.Protocol = ServerProtocol.ExchangeEWS

    ' you can also use Ms Graph API protocol -Office 365 
    ' oServer.Protocol = ServerProtocol.MsGraphApi

    ' set SSL connection
        oServer.ConnectType = SmtpConnectType.ConnectSSLAuto

    ' use  OAUTH 2.0 authentication
        oServer.AuthType = SmtpAuthType.XOAUTH2
    ' set user authentication
        oServer.User = userEmail
    ' use access token as password
        oServer.Password = accessToken

        Dim oMail As SmtpMail = New SmtpMail("TryIt")
        oMail.From = New MailAddress(userEmail)
        oMail.To.Add(New MailAddress("support@emailarchitect.net"))

        oMail.Subject = "test email sent from VB using Office365 OAUTH"
        oMail.TextBody = "test body"

        Dim oSmtp As SmtpClient = New SmtpClient
        oSmtp.SendMail(oServer, oMail)

        Console.WriteLine("The email has been submitted to server successfully!")

    Catch exp As Exception
        Console.WriteLine("Exception: {0}", exp.Message)
    End Try

End Sub
    


[C# - Send Email using Office365 OAUTH Authentication]

using System;
using EASendMail;

void SendMailWithXOAUTH2(string userEmail, string accessToken)
{
    try
    {
    // set Office365 EWS server address
        SmtpServer oServer = new SmtpServer("oultook.office365.com");

    // set Office365 Ms Graph API server address
    // SmtpServer oServer = new SmtpServer("https://graph.microsoft.com/v1.0/me/sendMail");

    // set Exchange Web Service protocol (EWS) -Office 365 
        oServer.Protocol = ServerProtocol.ExchangeEWS;

    // you can also use Ms Graph API protocol -Office 365 
    // oServer.Protocol = ServerProtocol.MsGraphApi;

    // enable SSL connection
        oServer.ConnectType = SmtpConnectType.ConnectSSLAuto;

    // use office365 OAUTH 2.0 authentication
        oServer.AuthType = SmtpAuthType.XOAUTH2;

    // set user authentication
        oServer.User = userEmail;
    // use access token as password
        oServer.Password = accessToken;

        SmtpMail oMail = new SmtpMail("TryIt");
        oMail.From = userEmail;
        oMail.To = "support@emailarchitect.net";

        oMail.Subject = "test email from Office365 account with OAUTH 2";
        oMail.TextBody = "this is a test email sent from c# project with Office365.";

        Console.WriteLine("start to send email using OAUTH 2.0 ...");

        SmtpClient oSmtp = new SmtpClient();
        oSmtp.SendMail(oServer, oMail);

        Console.WriteLine("The email has been submitted to server successfully!");
    }
    catch (Exception ep)
    {
        Console.WriteLine("Exception: {0}", ep.Message);
    }
}



[C++/CLI - using Office365 OAUTH Authentication]

using namespace System;
using namespace EASendMail;

void SendMailWithXOAUTH2(String^ userEmail, String^ accessToken)
{
    try
    {
    // Office365 server address
        SmtpServer ^oServer = gcnew SmtpServer("outlook.office365.com");

    // set Office365 Ms Graph API server address
    // SmtpServer ^oServer = gcnew SmtpServer("https://graph.microsoft.com/v1.0/me/sendMail");

    // set Exchange Web Service protocol (EWS) -Office 365 
        oServer->Protocol = ServerProtocol::ExchangeEWS;

    // you can also use Ms Graph API protocol -Office 365 
    // oServer->Protocol = ServerProtocol::MsGraphApi;

    // set SSL connection
        oServer->ConnectType = SmtpConnectType::ConnectSSLAuto;

    // use Office365 OAUTH 2.0 authentication
        oServer->AuthType = SmtpAuthType::XOAUTH2;

    //set user authentication
        oServer->User = userEmail;
    // use access token as password
        oServer->Password = accessToken;

        SmtpMail ^oMail = gcnew SmtpMail("TryIt");
        oMail->From = gcnew MailAddress(userEmail);
        oMail->To->Add(gcnew MailAddress("support@emailarchitect.net"));

        oMail->Subject = "test email sent from C++/CLI using Office365 OAUTH";
        oMail->TextBody = "test body";

        SmtpClient ^oSmtp = gcnew SmtpClient();
        oSmtp->SendMail(oServer, oMail);

        Console::WriteLine("The email has been submitted to server successfully!");
    }
    catch (System::Exception ^exp)
    {
        Console::WriteLine("Exception: {0}", exp->Message);
    }
}

Remarks

If your application is background service which doesn't support user interaction, please have a look at this topic: Use Office365 OAUTH with Background Service.

If you don't want to use OAUTH 2.0, Office 365 also supports traditional user authentication.

Online Tutorial

C# - Send Email using Google/Gmail OAuth 2.0 Authentication
C# - Send Email using Gmail/G Suite OAuth 2.0 in Background Service (Service Account)
C# - Send Email using Microsoft OAuth 2.0 (Modern Authentication) from Hotmail/Outlook Account
C# - Send Email using Microsoft OAuth 2.0 (Modern Authentication) + EWS Protocol from Office 365 Account
C# - Send Email using Microsoft OAuth 2.0 (Modern Authentication) + EWS Protocol from Office 365 in Background Service

VB - Send Email using Google/Gmail OAuth 2.0 Authentication
VB - Send Email using Gmail/G Suite OAuth 2.0 in Background Service (Service Account)
VB - Send Email using Microsoft OAuth 2.0 (Modern Authentication) from Hotmail/Outlook Account
VB - Send Email using Microsoft OAuth 2.0 (Modern Authentication) + EWS Protocol from Office 365 Account
VB - Send Email using Microsoft OAuth 2.0 (Modern Authentication) + EWS Protocol from Office 365 in Background Service

C++/CLI - Send Email using Google/Gmail OAuth 2.0 Authentication
C++/CLI - Send Email using Gmail/G Suite OAuth 2.0 in Background Service (Service Account)
C++/CLI - Send Email using Microsoft OAuth 2.0 (Modern Authentication) from Hotmail/Outlook Account
C++/CLI - Send Email using Microsoft OAuth 2.0 (Modern Authentication) + EWS Protocol from Office 365 Account
C++/CLI - Send Email using Microsoft OAuth 2.0 (Modern Authentication) + EWS Protocol from Office 365 in Background Service