Finally I solved the puzzle.

Before trying with the above code snippet, I tried to access my Exchange server through Outlook Web Access (OWA) from my browser. While doing so, the browser saved the prompted user-id (Administrator) and password in the password manager.

Hence, for the next time, when I tried to connect to the Exchange server using your code snippet, I got the following error message -

"Already tried to authenticate with null authentication realm at ${Exchange server name}, but still receiving: HTTP/1.1 401 Access Denied".

To overcome this, I just cleared the saved passwords in the browser settings. After doing so, the program works like a charm...!

Thank you.

Regards,
Dennis.