PLLTD, Is the Drac7 up to date? The current version is 1.20.20_A00. If not you may want to update it and then test it again. This is the page you find the appropriate version of the update - www.dell.com/.../poweredge-r720 Let me know how it goes.
I've got the iDRAC7 (enterprise) to send test email alerts so that it least works. I sent up email alerts so that when a hard drive fails, I get notified. Category: System Health Alert: Physical Disk Email: Checked.  What worries me that something is amiss is that I'm not getting constant email alerts right now that one of the Power Supply's is unplugged. If that doesn't work, how can I be sure that I will be notified if a hard drive fails? 
iDRAC7 - Email Alerts - Quick Question