ip.cesenanet.net has no MX records.
Question and response
Question
dig ip.cesenanet.net. MX
Answer
The response has no answer records.
Authority
ip.cesenanet.net. 86400 SOA dns2.cesenanet.com. dnsadmin.cesenanet.com. 2014040611 86400 7200 2592000 172800
Additional
The response has no additional records.