ns3.dreamhost.com has no MX records.
Question and response
Question
dig ns3.dreamhost.com. MX
Answer
The response has no answer records.
Authority
dreamhost.com. 300 SOA ns1.dreamhost.com. hostmaster.dreamhost.com. 2026022200 1460 1800 1209600 300
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0