Your mail host is not pointing to an smtp server.

Try referring to this article go get the right settings. Either relay or smtp server. https://support.google.com/a/answer/176600?hl=en

Also, you might need to create an app password for the authentication if you're using an individual gmail account. https://support.google.com/mail/answer/185833?hl=en#zippy=%2Cwhy-you-may-need-an-app-password