wap.cellularsouth.com has no MX records.
Question and response
Question
dig wap.cellularsouth.com. MX
Answer
The response has no answer records.
Authority
cellularsouth.com. 300 SOA ns1.p201.dns.oraclecloud.net. hostmaster.cellularsouth.com. 2023030704 3600 600 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0