While I am in, the recommendation in
(cited from the implementations link) to use regular expressions based
canonical breaks recipient validation and will cause backscatter.
which breaks the whole purpose of BATV INMHO.
I was wrong here. I missed the trick to "stack" proxy_filter's.
Also, whatever the scheme is, there is another class of applications
to think of. these are applications that use the sender address as an
element to determine the "reputation" of a transaction (spamassassin
AWL for instance). such apps should be made aware of the various BATV