mx01.lightboundhosting.com has no SRV records.
Question and response
Question
dig mx01.lightboundhosting.com. SRV
Answer
The response has no answer records.
Authority
lightboundhosting.com. 21600 SOA ns1.graysmark.net. hostmaster.graysmark.net. 2020091818 21600 3600 604800 21600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0