Declude never sees it anyway; never makes it to the queue. It errors
on the RCPT TO: line. With the Refuse Null Senders box checked, it
errors one command earlier, on MAIL FROM. Probably not enough to
make a difference.
Actually, it would be a significant difference under load. But this
Of course this means that most Out of office messages will not
make their way into your system
And you will be doing your users a great disservice by rejecting
hop-one bounces.
And you will get blacklisted.
There is no informed, rational reason to disable all messages from the
null
