Send mail via Google Apps Gmail using service account domain wide delegation in nodejs

Question

I\'ve been reading tutorials and seeing examples for 2 days already, with no success. I want to send an email using Google Apps Gmail account in NodeJS environment, however,

Answer 1

Thanks very much @agoldis. Both the summary steps and the code were very helpful.

It helped me pick up on a few things I needed to fix on both the GoogleWorkspace and the ApplicationCode end of the communication path. Below is my c# implementation for anyone who needs it.

private static void Try4()
{
  try {
     //file included in project with properties:  CopyToOutputDirectory = CopyAlways
     var credential = GoogleCredential.FromFile("MyPrj-MyServiceAccount-Credentials.json")       
                      .CreateScoped(new[] { GmailService.Scope.GmailSend })
                      .CreateWithUser("WhoIAmImpersonating@bla.com")
                      .UnderlyingCredential as ServiceAccountCredential;

     var service = new GmailService(new BaseClientService.Initializer() { HttpClientInitializer = credential });

     var nl = Environment.NewLine;
     string plainText =         "From:         WhoIAmImpersonating@bla.com" 
                         + nl + "To:           myfriend@gmail.com,"
                         + nl + "Subject:      This is the Subject" 
                         + nl + "Content-Type: text/html; charset=us-ascii" 
                         + nl 
                         + nl + "This is the message text.";
     var newMsg = new Message() { Raw = Base64UrlEncode(plainText) };

     service.Users.Messages.Send(newMsg, "WhoIAmImpersonating@bla.com").Execute();
     Console.WriteLine("Message Sent OK");
  }
  catch (Exception ex) {
      Console.WriteLine("Message failed");
  }
}



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