ANY queries to tinydns

Can someone tell me what the official behavior of
tinydns is supposed to be when an ANY query is
sent to it?  And preferably when the response
would be and wouldn't be larger than a udp packet.
Using wireshark it reports malformed response on
ANY queries to domains with a lot of records.

I'm trying to troubleshoot an issue with customers
we provide tinydns-based DNS service for who are
using Google for email and having delivery issues
from Yahoo (who appears to run qmail without the
big-DNS patch).  Google had been serving an ANY
response that was larger than unpatched qmail would
tolerate, I posted about it in a google forum and
they appear to have decreased the records that
are sent back in an ANY response now, which did
seem to solve the issues for most of the customers
who had reported it.  One customer has still had
the qmail cname error bounce on the Yahoo side so
they changed their name servers to a BIND-based
system and the problem went away, changed back to
our tinydns-based system and problem came back.
So I'm trying to figure out if we should be doing
something differently to not have the issue.  We
do not have axferdns running just FYI.  I also don't
see why our servers would even be involved as I'd
expect qmail to query for the ANY record on the
domain of the MX records, but maybe I'm wrong on
that.

Thanks,

David