Handle multiple lines output to send by email

Hi , guys , im sending emails from my mkt device with:

/tool e-mail send file=backup  to="leandro@pepe.com.ar" body=$body  subject="system_backup_$[/system identity get name]"

I would like to set the $body variable to send the output of:

/system resource print

How can I do it ?
So far , I can grab one line by one doing:

[:tostr [/system resource get value-name=board-name]]

But … I think there should be a better and faster way.
Any idea, would be pretiated.
Regards.
Leandro