System mail setting Test send email failed

After i have set correctly email setting in Admin > Email Settings. I click test email and get following error message show in suitecrm.log

SugarPHPMailer encountered an error:: An outgoing mail server is not configured to send emails. Please configure an outgoing mail server or select an outgoing mail server for the mail account that you are using in Settings >> Mail Account.

My Suitecrm version 7.6.6

Pls help

The Email>Settings>Outgoing Mail Server>Send Test Email is working fine, but not for the Admin >Email Settings