Please follow the link:
https://egov.immigration.gov/cris/jsps/index.jsp
and you will see the following message of last section of the page:
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Case Status Portfolio with Updates via Email
USCIS Customers (single applicant) and Representatives (representing many cases, such as lawyers, charitable groups, or corporations) who require regular access to status information about multiple cases can create an account to more conveniently access this information. The services provided are identical, except Representatives may also enter their own internal office tracking number with each receipt number.
In addition, you can choose to receive automatic case status updates, which will be sent via email.
Create/Edit customer portfolio account
Create/Edit representative portfolio account
Login to an existing account.
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You should create a portfolio account there to get the email alerts.
They (atterney and friend) both got the approval notices by mail (friend got courtesy copy of it)