mailgw.ibw.com has no MX records.
Question and response
Question
dig mailgw.ibw.com. MX
Answer
The response has no answer records.
Authority
ibw.com. 3600 SOA ns1.intercom.com.sv. hostmaster.intercom.com.sv. 20210793 86400 7200 3600000 172800
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0