The service account needs to be authorized or it cant access the emails for the domain. “Client is unauthorized to retrieve access tokens using this method” Means that you have not authorized it properly check Delegating domain-wide authority to the service account
I ran into the same issue with the Google API’s. The main issue here is if you install the Microsoft Http Client Libraries it puts in your project an updated version of the System.Net.Http.Primitives DLL. The web.config assumes you are still using the default version of 1.5. There are two things that need to happen … Read more
According to the .NET user guide: Download the .NET client library: Add these using statements: using Google.GData.Client; using Google.GData.Extensions; using Google.GData.Spreadsheets; Authenticate: SpreadsheetsService myService = new SpreadsheetsService(“exampleCo-exampleApp-1”); myService.setUserCredentials(“jo@gmail.com”, “mypassword”); Get a list of spreadsheets: SpreadsheetQuery query = new SpreadsheetQuery(); SpreadsheetFeed feed = myService.Query(query); Console.WriteLine(“Your spreadsheets: “); foreach (SpreadsheetEntry entry in feed.Entries) { Console.WriteLine(entry.Title.Text); } Given … Read more