smtp.rapidswitch.com has no MX records.
Question and response
Question
dig smtp.rapidswitch.com. MX
Answer
The response has no answer records.
Authority
rapidswitch.com. 10800 SOA ns2.rapidswitch.com. hostmaster.rapidswitch.com. 98 3600 120 1209600 10800
Additional
ns2.rapidswitch.com. 1200 A 87.117.237.66
. 0 OPT ; payload 1280, xrcode 0, version 0, flags 0