Facing issue Send Email though MS Graph Delegated permission

Question

I want to send email from service account through delegated permission, I tried two approaches but getting error while sending email: Approach 1:

Approach IPublicClientApplication publicClientApplication = PublicClientApplicationBuilder
        .Create("ClientId")
        .WithTenantId("TenantId")
        .Build();
  UsernamePasswordProvider authProvider = new UsernamePasswordProvider(publicClientApplication);
  GraphServiceClient _graphClient = new GraphServiceClient(authProvider);
await _graphClient.Me
      .SendMail(message, true)
       .Request().WithUsernamePassword("ServiceAccountUser", "ServiceAccountUserPassword")
      .PostAsync().ConfigureAwait(false);

Error: The given key 'Microsoft.Graph.AuthenticationHandlerOption' was not present in the dictionary. Approach 2:

 string[] scopes = { "Mail.Send" };
  var options = new UsernamePasswordCredentialOptions
 {
     AuthorityHost = AzureAuthorityHosts.AzurePublicCloud,
 };
 var userNamePasswordCredential = new UsernamePasswordCredential(
            "ServiceAccountUser", "ServiceAccountUserPassword", tenantId, clientId, options);
 var graphClient = new GraphServiceClient(userNamePasswordCredential, scopes);
 await graphClient.Me
         .SendMail(message, true)
          .Request()
         .PostAsync().ConfigureAwait(false);

Error: Code: generalException
Message: An error occurred sending the request.
UsernamePasswordCredential authentication failed: AADSTS65001: The user or administrator has not consented to use the application with ID 'DumyId' named 'DumyName'. Send an interactive authorization request for this user and resource. Added Permission: Query: I want to send an email from my Azure Web application from Service Account through MS Graph, can you please help me to move forward ?

Answer 1

Hello Akhil, Admin consent needs to be provided or you will need to have one pop-up authentication windows authenticating user. Please refer following reference:
https://learn.microsoft.com/en-us/graph/permissions-overview?tabs=http

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