mail.yourhostingaccount.com has no MX records.
Question and response
Question
dig mail.yourhostingaccount.com. MX
Answer
The response has no answer records.
Authority
yourhostingaccount.com. 3600 SOA ns1.yourhostingaccount.com. admin.yourhostingaccount.com. 2004012801 10800 3600 700000 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0