[dns-operations] Why would an MTA issue an ANY query instead of an MX query?

[Stephane Bortzmeyer]

On Sun, Jun 10, 2012 at 06:47:22PM +0200,
 sthaug at nethelp.no <sthaug at nethelp.no> wrote 
 a message of 44 lines which said:

> limiting EDNS responses to 1460 bytes, as suggested [by me], will
> block quite a few legitimate replies (not just ANY replies).

Why? The response will be sent, just with a TC bit, and the client, if
it is not lying about its IP address, will retry with TCP. No
blocking.