(Java) Office365 Send Email using SMTP with OAuth2 Authentication

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Demonstrates how to send email from smtp.office365.com using OAuth2 authentication.

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import com.chilkatsoft.*;

public class ChilkatExample {

  static {
    try {
        System.loadLibrary("chilkat");
    } catch (UnsatisfiedLinkError e) {
      System.err.println("Native code library failed to load.\n" + e);
      System.exit(1);
    }
  }

  public static void main(String argv[])
  {
    // This example requires the Chilkat API to have been previously unlocked.
    // See Global Unlock Sample for sample code.

    // An Office365 OAuth2 access token must first be obtained prior
    // to running this code.

    // Getting the OAuth2 access token for the 1st time requires the O365 account owner's 
    // interactive authorization via a web browser.  Afterwards, the access token
    // can be repeatedly refreshed automatically (with no user interaction).

    // See the following examples for getting and refreshing an OAuth2 access token

    // Get Office365 SMTP/IMAP/POP3 OAuth2 Access Token
    // Refresh Office365 SMTP/IMAP/POP3 OAuth2 Access Token

    // First get our previously obtained OAuth2 access token.
    CkJsonObject jsonToken = new CkJsonObject();
    boolean success = jsonToken.LoadFile("qa_data/tokens/office365.json");

    CkMailMan mailman = new CkMailMan();

    mailman.put_SmtpHost("smtp.office365.com");
    mailman.put_SmtpPort(587);
    mailman.put_StartTLS(true);

    // Use your Office365 email address for the SmtpUsername.
    mailman.put_SmtpUsername("OFFICE365_EMAIL_ADDRESS");
    mailman.put_OAuth2AccessToken(jsonToken.stringOf("access_token"));

    // Create a new email object
    CkEmail email = new CkEmail();

    email.put_Subject("This is a test");
    email.put_Body("This is a test");
    email.put_From("MY_NAME <OFFICE365_EMAIL_ADDRESS>");
    success = email.AddTo("John Doe","somebody@example.com");

    // Call SendEmail to connect to the SMTP server and send.
    // The connection (i.e. session) to the SMTP server remains
    // open so that subsequent SendEmail calls may use the
    // same connection.  
    success = mailman.SendEmail(email);
    if (success != true) {
        System.out.println(mailman.lastErrorText());
        return;
        }

    // If SendEmail failed because of "Failed to get initial SMTP Response", then it may be 
    // a firewall or anti-virus blocking communications.
    // See https://cknotes.com/smtp-office365-com-failed-to-get-initial-smtp-response/

    success = mailman.CloseSmtpConnection();
    if (success != true) {
        System.out.println("Connection to SMTP server not closed cleanly.");
        }

    System.out.println("Mail Sent!");
  }
}