In SharePoint 2010 I noticed I wasn’t receiving updates when people posted stuff on my MySite.

Turns out, my Active Directory Sync is not working, and my email account was not being populated in my User Profile.

Fix it!

Central Administration –> Manage User Profiles
Find the person having the issue.
Update the email address.
Cruise over to the mysite, post a note, look in your inbox for an email.