From: Keith Moore <moore(_at_)cs(_dot_)utk(_dot_)edu>
...
That is the same sort of reasoning that spammers use to justify
their activities.
it's also the same sort of reasoning that you used to justify
sending this mail to the IETF list.
You know that is a false statement.
it's as true as your statement was, and for the same reason.
You know that subscribers to this
list ask to receive all of the good stuff with the drivel, except for
the out-right spam and the messages from banned individuals. You also
know that no one asks to have their SMTP servers do a useless cycle
in addition to receiving an auto-response.
they don't ask to have their DNS servers queried either. nor do they ask
to have their SYNs ACKed. actually very few users try to specify how a
service should be implemented, they just want it to work well.
- bounces would not bog down your mail servers, since you can discard
or otherwise deal with bounces with no more "bogging" than you are
spending poking at other people's systems.
for a variety of reasons, that's simply not true for the cases where
I'm using it.
How did I guess you would see things that way? It is, of course,
nonsense, because you could arrange to not receive any bounces just
as some spammers do.
I *want* to receive some kinds of bounces, because they give me clues
about how well the system is working. But I see absolutely no reason
to send large files to people who don't supply a valid return address,
nor to do database searches for them, nor to try to process commands
that they send to a command interpreter.
(Many spammers want to receive bounces to clean their
lists, because some big ISPs and others automatically black-list
SMTP clients after they've sent to too many bad addresses.)
perhaps, but even the spammers who clean their recipient lists don't
necessarily use valid return addresses, and it's the return addresses
that I'm checking.
That's nonsense that you would see as such if you were not stuck
on rationalizing that which you know is dubious. Spamemrs who want
bounces to clean their lists do indeed use valid return addresses.
You must get spam from different folks than I do, then. If the spammers
use SMTP RCPT to cull bad addresses from their lists I'm not at all
surprised, but most of the spam I see still comes from people who want
to hide their tracks for the actual spam.
- a mechanism that could really determine that addresses are valid
could be useful in a web page to provide immediate feedback to
users. The reality of MX servers, firewalls, sendmail "catch-all"
maps, and other things make the RCPT command too unreliable to use
for that purpose.
BS. a simple syntax check isn't perfect either, but it's useful to
catch some errors. this catches some more errors, without exhibiting
false positives. it also has a cost, which is why I haven't
recommended it for general use. but that doesn't mean it is useless.
Charges of "BS" from someone who admits never having measure the
effectiveness of the mechanism are ironic.
No, you're trying to insist that I define "effectiveness" in your terms.
Keith