mx.arubacloud.com has no MX records.
Question and response
Question
dig mx.arubacloud.com. MX
Answer
The response has no answer records.
Authority
arubacloud.com. 300 SOA arudns1.aruba.it. hostmaster.aruba.it. 2026021201 86400 7200 2592000 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0