You can create the daily notification for the same.
Steps are below
Open and login to the SEPM
Click Monitors
Click Notifications
Click Notification Conditions
Click Add
Select "Virus definitions out-of-date"
Enter the notification name(eg- old defintion)
Select condition ( virus definitions older than 25 and so on days )
Add your email id here.
Option 2:
You can export compuer status report also you can find out of defination report.
Monitors -> logs -> computer status
Option 3
Some of Sql query availabled
https://www-secure.symantec.com/connect/articles/compilation-sql-queries-sepm-database
edit
See this thread https://www-secure.symantec.com/connect/forums/sepm-121-clients-old-definitions-report