missing out-of-zone data in addtional section

[Jonathan de Boyne Pollard]

o> This problem [...]

... is only a problem in your perception.  It is not, in fact, a problem 
at all.  "Additional" section processing for "MX" resource record sets 
is purely an optimisation.  It is not intrinsically necessary, as 
"additional" section processing for "NS" resource record sets is.  Also 
note that you are querying a proxy DNS server.  "Additional" section 
processing, of any sort, is not intrinsically necessary for proxy DNS 
servers, only for content DNS servers.  (Indeed, "additional" section 
processing by proxy DNS servers is wasted bandwidth as far as most DNS 
Client libraries and application programs are concerned. They'll take 
the resource record set that they _actually asked for_, and discard the 
remainder of the response.)

o> [...] is possibly the cause of some problems I'm having mailing 
companies
o> whose domains they host.

No, it isn't.  The cause of those problems, whatever they are, lies 
elsewhere.  The mail system error messages will tell you where.