11/11 Simple question I suppose, but this happened to me with an ISP in
Japan. Have two email accounts set up. First account has forwarding
to the second account. The 2nd account recently set up a vacation
reply. So mail arrives in first account, is forwarded to 2nd account,
which in turn generates vacation reply, which the first account gets,
it forwards that email, another vacation response is generated and
received, etc, etc. Pandemonium ensues. The ISP called it a
denial-of-service attack and is threatening to cut off service. But
this was an honest mistake (2nd account is used by a colleague and he
set up vacation response on his client without telling me.) Question:
would any other ISP (or Soda) have been able to prevent this, or at
least stop it before it brought down their system?
\_ a reasonable vacation reply mechanism would implement loop
detection headers and/or duplicate message-id checks (as should
any other auto-responder).
\_ Not to mention keeping track of recipients. Your first
ISP should also have some kind of reasonable loop detection.
Tell them both that the gaijin tech gods have spoken and that
they should get /<l00 or we'll whip out the black ships. -John
\- Thanks for the replies. Should these checks have been
implemented on server software, client software (maybe there is
a setting for "reply once"?), or both?
\_ basic rule of computing: never trust clients, never rely on
clients to do the right thing. your isps are both stupid.
\_ Not even a 'trust' question--this is basic mail server
config 101.
\_ I was making a more general statement about all client/
server relationships, not just mail.
\_ But isn't a vacation responses a separate piece of e-mail
similar to when the user does a reply, instead of a re-route of
the original? How does loop detection help in this case?
\_ It should not be similar; it should have a Precedence: junk
header, among other things. And as noted above, the vacation
program should keep track of recipients. -tom
\_ it should notice its own message sent back to itself and
not reply. this would solve OP's problem. you are right
that this might not help two vacation systems in a volley,
but that is caught by not sending vacation notices to the
same recipient within some time period, e.g. a week. |
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