On Sun, Jul 22, 2001 at 10:24:10AM -0400, Dave C. wrote:
> Er, that would only happen if the MTA's for all 10,000 users were doing
> SMTP callback. The exploder wouldnt do a callback for each recpient,
Yes. I know it's not a problem now, my thought was "what if everyone were
doing like me?"
> only one for the sender as it received the message. If the sender
> somehow send out 10,000 individual messages, to 10,000 systems that all
> supported SMTP callback, then they would get 10,000 callbacks, but if
> they can handle 10,000 outbound sessions, surely they can handle the
> callbacks. Now I suppose theres nothing stopping them from pointing the
No, you're forgetting that by default SMTP callback is on the header sender
too.
What this means is that when you send a message to exim-users, if exim-users
sends it to 10,000 users, it could get 10,000 SMTP callbacks for the
envelope sender, but you could get 10,000 SMTP callbacks for the header
sender too.
If you have a slow system being a slow dialup link, that could be anoying.
> callbacks somewhere else.. Hrm.. Perhaps exim should cache the last N
> callback results? No.. one could get around that by generating a new
> random username each time..
Exim should probably cache callbacks. Not necessarily to prevent DDOS, but
to avoid bothering the remote systems for every Email they send (especially
with my crude patch that also checks for postmaster every single time)
I wouldn't have a problem with exim caching each callback for a few days,
even a week or two, even if it means that on a system like SF, I'd end up
with a huge database.
Marc
--
Microsoft is to operating systems & security ....
.... what McDonalds is to gourmet cooking
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