mail.skylinux.com has no TXT records.
Question and response
Question
dig mail.skylinux.com. TXT
Answer
The response has no answer records.
Authority
skylinux.com. 3600 SOA ns.skylinux.org. domain.skylinux.org. 2014012803 43200 10800 1209600 3600
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0