Troubleshooting a '550 Access Denied - Invalid HELO name’ error
All of our servers require SMTP authentication to send emails. When sending an email using an email application on your computers such as Outlook, Thunderbird, or Mac Mail and you receive the error “550 Access denied - Invalid HELO name,” it means you have not ticked the option “My outgoing server (SMTP) requires authentication” in your email application. If you are using one of our dedicated email hosting plans, a Google Workspace account, or using email through a web hosting service, follow these steps to enable this feature in typical email applications. Please see below:
From the Menu Bar, click Tools, then Account Settings.
This will bring up the Account Settings window, where you can click on Outgoing Server (SMTP) at the bottom of the list on the left side of the window.
In the middle of the window, select the appropriate outgoing server and click the “Edit” button.
Make sure the “Authentication method” is set to “Normal password.”
Click OK to close the SMTP edit window and again on the Account Settings window.