You should be able to do this in 'Automatic Responses' in your ePO console (Menu > Automation > Automatic Responses).
Event Group: ePO Notification Events
Event type: Server
Event Description: Equals Master Repository Update failed OR Equals Master Repository Update succeeded
I still don't quite understand the logic of the Aggregation tab in Automatic Responses (it's not clear to me how you can create a 'digest' of x days/hours/etc.), but it is really your preference anyways.
<recipients = your email>
Subject: Repository Update Details
(you can insert the above variables through the dropdown boxes below the body)
Hopefully this is of some help and gets you something close to what you're looking for.
Moved this to ePO as a more appropriate spot.