nsb.ups.com has no MX records.
Question and response
Question
dig nsb.ups.com. MX
Answer
The response has no answer records.
Authority
ups.com. 3600 SOA ibx.ups.com. hostmaster.nowhere.null. 2023427823 21600 1800 2419200 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0