Someone on ExpertsExchange found the solution: you need to check the box in the "State" column on the System->Alerts->Email Alert Settings page for the destination email address line(s).  "Enabled" would be a much better label for that column, as "state" meant nothing to me...
I'm trying to test out email alerts using iDRAC6 on a PE T610 server.  I was able to configure iDRAC's Email Alert Settings and successfully did a Test E-Mail [Send].  My next step is to test whether an email alert gets sent when a monitored hardware event occurs.  As far as alert config: under Alerts->Platform Events I have Enable Platform Event Filter Alerts enabled, and under Platform Event Filters List, all Events are enabled (the default).  My test - I simply unplugged one of the 2 power supplies from 110V outlet for about 10 seconds.  No email alert was sent.  When I look at Logs->System Event Log, I do see 2 critical events(red circle with white X):  one says "The power input for power supply 2 is lost", other "Power supply redundancy is lost". Is it possible a 10 second loss of power on one supply is not severe enough to trigger a true alert?  I'm not buying that, as the critical events are recorded in the system log... Maybe there is something further I have to configure?   TIA, Mike  
iDRAC6 on PE T610: test SMTP alerts by unplugging one of the power supplies did 
NOT send an email