mx4.printhosting.com has no CNAME records.
Question and response
Question
dig mx4.printhosting.com. NS
Answer
The response has no answer records.
Authority
printhosting.com. 764 SOA ihsaddc01.printhosting.com. dom-admin.efi.com. 5934355 900 600 172800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0