Use Google OAuth for email delivery
Go to Manage > Mailboxes > Open the desired Mailbox > Connection Settings > Outgoing. Select Gmail.
Click Connect Google and the next screen will take you to the permissions page to allow Help Ninja to access your Google account. Click the Allow button.
Now, you will be redirected to your Help Ninja Mailbox page. Please remember that you can revoke access to your Google account anytime and use an alternate SMTP server to send emails.