Normally the email is 2 working days after the Ghost Update
Maybe someone can confirm?
There is no email for updates on the citizenship portion, maybe for PR and other things we did have emails for updates.
Right now, if your "Updated" date changes and no update shows up in the list, that means it's a "ghost" update and something happened on your file. Most times an update will follow in 2 days. Sometimes a ghost update does not follow up with an actual update, that would be because something happened but no notable milestone to report.
The tracker lags behind GCMS for 48-72 hours. so updates usually show up 2 days after the date they are made.
The officials do send actual emails about your applications in the case they need something (like fingerprints, passport copy) or if you need to take a test, or if you need to attend an oath.