ASPMX5.GOOGLEMAIL.COM has no CNAME records.
Question and response
Question
dig ASPMX5.GOOGLEMAIL.COM. NS
Answer
The response has no answer records.
Authority
GOOGLEMAIL.COM. 13 SOA ns1.google.COM. dns-admin.google.COM. 873285235 900 900 1800 60
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0