[zonecheck-tests] incorrect failure for "hostmaster MX is not an alias"

[Salemme, Mary E]

Hello,

I am a DNS administrator for digex.com name servers.  Some of our
customers have had problems registering/renewing their .fr domains
because their registrars are using Zonecheck which is reporting a fatal
error.  

As an example, testing digex.com returns this result:

--

ZoneCheck: digex.com.
Zone information
 digex.com. 
 mia01.digex.com. 216.255.129.249 
 mia02.digex.com. 216.255.130.249 

Test results
---- fatal ----
 [TEST MX is not an alias]: server failure (IN/CNAME:
esmtp00.verizonbusiness.com.)
mia01.digex.com./216.255.129.249 

--

Zonecheck reports a failure for "hostmaster MX is not an alias".
However, our hostmaster address is
address@hidden, and the target of the MX record
for verizonbusiness.com is not an alias.

~$dig mx verizonbusiness.com +sh
10 esmtp00.verizonbusiness.com.
~$dig esmtp00.verizonbusiness.com +sh
199.249.25.205
198.4.8.173

Is this a bug in Zonecheck or is there something we need to do on our
end?

Thanks,
Mary