Our UAT instance is refreshed from Prod, so it's got identical users and (I assume) user preference settings.
If I send an announcement in UAT, is there any chance that customers could receive an email about it?
Part of the PROD to UAT refresh process should obfuscate each user's email address. To confirm this you can navigate to your admin console >> people tab and see that @localhost has been added to each user's email. If you are seeing this your UAT instance should not send out emails to these users.
Thanks, that's exactly what I needed to know.