There is an option on the portal which has a checkmark for monthly updates - I thought that is why I got an update notification after a month but when I checked the dates did not match. So, my best guess is that as the VOs make progress on the application and enter data, system sends these updates to users. This is a programmer's mistake and since some people are reporting multiple e-mail like this then it's a system wide issue throughout the process.
Only good thing out of this is that you are not forgotten and your application is in process.
By the way, which office did you apply to and what is your timelines?