Need some help with unbound DNS

Hey, I'm looking for a little help with unbound.

I'm playing around with the pfsense 2.2 beta and they're using unbound now instead of dnsmasq for the built in DNS resolver. I want to add an MX record to the advanced options but I have no idea how to write a MX record for unbound. For some reason I can't seem to find it by googling so I thought maybe someone here would know. I just need a quick explanation of how to write an MX record for unbound so can see if I can get it working.

As far as im aware it would follow something along the lines of this

local-data: "example.com. IN MX 10 mail.example.com."

heres the man page https://unbound.net/documentation/unbound.conf.html

Thanks, I'll give that a go.