cloudapp.net has no MX records.
Question and response
Question
dig cloudapp.net. MX
Answer
The response has no answer records.
Authority
cloudapp.net. 60 SOA ns1-201.azure-dns.com. msnhst.microsoft.com. 2107898940 900 300 604800 60
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0