mailrelay.rentedapps.com has no MX records.
Question and response
Question
dig mailrelay.rentedapps.com. MX
Answer
The response has no answer records.
Authority
rentedapps.com. 1800 SOA dns01.rentedapps.com. hostmaster.rentedapps.com. 450 900 1200 86400 3600
Additional
. 0 OPT ; payload 4000, xrcode 0, version 0, flags 0