Send email using gmail api in C#

static string[] Scopes = { GmailService.Scope.GmailSend };

string plainText = "To: ra******@gmail.com,r*****@infosec.com\r\n" +
                               "Subject: subject Test\r\n" +
                               "Content-Type: text/html; charset=us-ascii\r\n\r\n" +
                               "<h1>Body Test </h1>";
            
var newMsg = new Google.Apis.Gmail.v1.Data.Message();
newMsg.Raw = Program.Base64UrlEncode(plainText.ToString());
service.Users.Messages.Send(newMsg, "me").Execute();

public static string Base64UrlEncode(string input)
      {
          var inputBytes = System.Text.Encoding.UTF8.GetBytes(input);
          return Convert.ToBase64String(inputBytes).Replace("+", "-").Replace("/", "_").Replace("=", "");
      }

Dim Scopes = GmailService.Scope.GmailSend
        Dim ApplicationName As String = "Gmail API .NET Quickstart"

        Dim credential As UserCredential
        Dim stream = New FileStream(My.Application.Info.DirectoryPath + "\client_secret.json", FileMode.Open, FileAccess.Read)
        Dim credPath As String = My.Application.Info.DirectoryPath + "\"
        credential = GoogleWebAuthorizationBroker.AuthorizeAsync(GoogleClientSecrets.Load(stream).Secrets, {Scopes}, "user", CancellationToken.None, New FileDataStore(credPath, True)).Result
        stream.Close()
        Dim service = New GmailService(New BaseClientService.Initializer() With {.HttpClientInitializer = credential, .ApplicationName = ApplicationName})
        ' Define parameters of request.
        Dim request As UsersResource.LabelsResource.ListRequest = service.Users.Labels.List("me")
        ' List labels.
        Dim Labels As IList
        Labels = request.Execute().Labels

        If IsDBNull(Labels) = False And Labels.Count > 0 Then
            Dim labelItem As Label
            For Each labelItem In Labels
                Console.WriteLine("{0}", labelItem.Name)
            Next
        Else
            Console.WriteLine("No labels found.")
        End If
        Console.Read()


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