[Exim] Anything wrong with rejecting bounces for addresses w…

We've got a few valid recipient addresses which basically receive mail
to be forwarded to a small team of minders, but the address itself
never sends mail. For example, a collective address for the web
server support staff (yes, both of us ;-).

Some of these addresses are being faked as envelope sender addresses
(on spam, viruses etc) to a degree which is out of all proportion to
the more usual rate of collateral bounce spams per user. One, for
example, has already received 150 bounces so far this week, reporting
rejection or other non-delivery causes from third parties, for stuff
that it never sent.

I've now started rejecting mails which have null envelope senders and
are addressed to some of these "receive-only" addresses, with the
response:

| This address does not send mail; nondelivery reports are rejected as fakes.

Does the team think this is a reasonable thing to do? Is the message
clear enough? Am I missing some unexpected knock-on effect? Sure,
we'll now also repudiate this address if a callout is attempted for
it, but as it's only active for receipt of mail (viz. mail which has
non-null envelope sender), and never actually sends anything, this
seems to me to be not only harmless, but possibly even beneficial, no?

cheers