Solution to: Outlook error - The server responded: 550 Access denied - Invalid HELO name (See RFC2821 4.1.1.1

Have you experience the error message below in outlook. Well I faced the same issue a while ago when I tried to add my email account in outlook 2013. And I share to you how I fix this.

Send test e-mail: The connection to the server was interrupted. If this
problem continues, contact your server administrator or Internet service provider
(ISP). The server responded: 550 Access denied - Invalid HELO name (See RFC2821 4.1.1.1)

To fix this problem

Open your Outlook - Go to>Account Setting>click change or repair> click more Settings

On Outgoing Server tab Checked the My outgoing server(SMTP) requires authentication.

Enjoy Sending!!!