what am I dealing with here?

[admin at lctn.org]

As long as kms.k12.mn.us has even just an A record in DNS, it will 
get spam directed to that address. 

Removing the 10 kms.k12.mn.us MX might help, but probably not 
completely. 

All our schools configure their firewall, so they only receive mail from our mailscanner. We leave the MX record in place, incase our server goes down, so they will still get their mail by removing the rule. 
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