spf2.swservers.com has no MX records.
Question and response
Question
dig spf2.swservers.com. MX
Answer
The response has no answer records.
Authority
swservers.com. 3600 SOA dns.swservers.com. hostmaster.swservers.com. 1736564617 43200 3600 604800 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0