mx1.limestonenetworks.com has no SRV records.
Question and response
Question
dig mail.lsncorp.net. SRV
Answer
The response has no answer records.
Authority
lsncorp.net. 1800 SOA denver.ns.cloudflare.com. dns.cloudflare.com. 2397604745 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0