iristelwireless.com has no MX records.
Question and response
Question
dig iristelwireless.com. MX
Answer
The response has no answer records.
Authority
iristelwireless.com. 86400 SOA pdns104.ultradns.com. tldadmin.iristel.com. 2018061106 86400 86400 86400 86400
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0