I was trying to set up MS Outlook 2016 to work with Gmail, but the default settings simply do not work.
You will first need to make changes in your Gmail settings that are described here: https://support.google.com/mail/answer/7126229.
Then when setting up your Outlook client, do it manually, and go deep into the settings to change the incoming and outgoing ports to match what are on the page linked above, turning on authentication for outgoing mail.
Next, if you have 2-Step Verification for your Google Accounts (which I recommend you do, for better security), you'll find that your gmail password will not work to connect through Outlook. You will need to add an "App password" for Outlook at this link https://security.google.com/settings/security/apppasswords.
More detailed instructions on how to set up an "App password" for Outlook can be found here: https://www.msoutlook.info/question/902.
