Mark,
A EDNS referral from the root servers to the COM servers
already exceeded 512 bytes. The world hasn't fallen over.
Actually, I was thinking to myself yesterday that the email world is going to be awfully
fun when IPv6 sets in and we're all running mail servers with nice long AAAA records such as
fc00:836b:4917::a180:4179.
I think you might have missed the point of my post.
It was a tounge in cheek reply to the poster who suggested bad things happen if the DNS message size exceeds 512 bytes.
He was commenting about AOL's MX records which currently weigh in at 507 bytes.
Therefore if we were to hypothesise that the world ends at 512 bytes, then companies doing things the way AOL does, but using IPv6 addresses rather than IPv4 addresses for their MX records could run into "problems".
Hope that clarifies 