mail.oss.centurylink.net has no MX records.
Question and response
Question
dig mail.oss.centurylink.net. MX
Answer
The response has no answer records.
Authority
oss.centurylink.net. 3600 SOA authns2.qwest.net. abuse.aup.lumen.com. 2260206000 10800 3600 604800 3600
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0