subs.ibrowse.com has no MX records.
Question and response
Question
dig subs.ibrowse.com. MX
Answer
The response has no answer records.
Authority
subs.ibrowse.com. 3600 SOA ns1.ibrowse.com. netadmin.ibrowse.com. 2020021801 3600 1800 1209600 3600
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0