ADMIN SETTINGS THAT MUST BE UPDATED IN PERSONAL GSUITE TO ALLOW SEND AS
By default, users cannot use an outbound gateway. The G Suite mail servers deliver all outgoing mail, including mail that uses alternate From addresses.
To allow users to use an outbound gateway:
2. From the Admin console Home page, go to Left Panel click AppsGoogle WorkspaceGmailEnd User Access.
Tip: If the agent does not see END USER ACCESS have them log out, log back into Google Admin with an Incognito Window, and they should see it. Previously the END USER ACCESS option used to be all the way to the bottom, and in fact the article from Google itself says that, but it is no longer the case. Here is a screenshot of where it is now:
3. In the Allow per-user outbound gateways section, select Allow users to send mail through an external SMTP server when configuring a "from" address hosted outside your email domains.
4. When this check box is selected, users who associate additional email addresses with their accounts can enter connection information for an alternate SMTP server. Learn more about the required steps for the user. When the check box is not selected, users cannot specify an SMTP server for the additional address.
5. At the bottom, click Save.
It can take up to 24 hours for changes to propagate to all user accounts.
Once this option is enabled, users can configure their alternate email addresses to use an outbound gateway.
Each user must configure this option individually. Learn more about how the user does it.
Once this change has happened you can now add your Alias to your email. Follow the instructions below that apply to you.