zimbra.clientaes.com has no MX records.
Question and response
Question
dig zimbra.clientaes.com. MX
Answer
The response has no answer records.
Authority
clientaes.com. 1800 SOA graham.ns.cloudflare.com. dns.cloudflare.com. 2396974114 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0