ns1.reedelsevier.com has no MX records.
Question and response
Question
dig ns1.reedelsevier.com. MX
Answer
The response has no answer records.
Authority
reedelsevier.com. 900 SOA spn5061.telecom.regn.net. hostmaster.lexisnexis.com. 2800 3600 900 2419200 900
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0