outbound-smtp45.blacknight.com has no MX records.
Question and response
Question
dig outbound-smtp45.blacknight.com. MX
Answer
The response has no answer records.
Authority
blacknight.com. 3600 SOA ns1.blacknight.com. hostmaster.blacknight.com. 1276183043 14400 7200 2419200 3600
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0