smtp03.can.sabacloud.com has no SRV records.
Question and response
Question
dig smtp03.can.sabacloud.com. SRV
Answer
The response has no answer records.
Authority
can.sabacloud.com. 1800 SOA dns1.p01.nsone.net. hostmaster.nsone.net. 1683951715 3600 600 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0