Set e-mail configuration in WSUS API
We can configure a new WSUS server using the COM API and PowerShell cmdlets for every option in the UI except for setting the e-mail notifications.
...but there's no way to Set them.
At my company, the build is fully automated including installation and configuration of WSUS, but for the e-mail notification settings.
Rich B commented
For clarity, we can access the IUpdateServer.GetEmailNotificationConfiguration() interface from PowerShell, and do things like set the SmtpHostName, Sender e-mail address, and time to send notifications, but we can't set the StatusNotificationRecipients and SyncNotificationRecipients lists. We can configure everything except for who to actually send the notifications to, which kind of makes this part of the interface pointless.