Send special crafted text in mail notification

I have a host where I’m both sending a UP/DOWN mail notification to an admin mail and also another mail.

Now, I wounder if and how I can send my own text that other mail adress.

Currently the mails loks like this:

***** Host Monitoring on icinga *****

test is DOWN!

Info:    CRITICAL - Host Unreachable (172.18.7.71)

When:    2019-08-22 14:52:50 +0200
Host:    test
IPv4:	 172.18.7.71

For that other email address I would like to send a string like “X is down, please go and restart the computer”.

Is that possible?