Comment # 4 on bug 920205 from Neil Brown

One thing you could do straight away if you like is to write a little script to
send you email and set it as MDADM_PROGRAM in /etc/sysconfig/mdadm

Something like

#!/bin/sh
mail -s "md monitor message" root@localhost << END
Array: $2
Event: $1
Extra: $3
END

That will send you email for every event.  You can obviously  make it
conditional if you like.