Is there any way to customize the email alert such as email subject, body?
Thanks you guys, I'll try it.
You can completely customise the email subject and body using Custom Notification Methods for NMIS Events.
There is a good example of this in /usr/local/nmis8/lib/Notify/critical.pm
Opmantek also has a product opEvents which great when you want even more control over notifications and escalations than NMIS has. opEvents includes the ability to create notifications from syslog and SNMP traps as well.
Yes, this is possible, you can find the steps in the community.