[lug] A .forward standoff
hugh at math.byu.edu
Tue Jun 14 15:57:14 MDT 2005
I mispoke slightly. The message would die after hitting a maximal hop
count. However you could cause all sorts of messes and manual
intervention may be required to stop the loop.
e.g. in sendmail you could do
in the aliases file that would cause the ~user/.forward file to be ignored
until the offending .forward file were fixed.
I asked a colleague and he said that they had a user once with accounts on
three separate servers and would forward mail on each server to the other
e.g. A would forward to B and C; B would forward to A and C; C would
forward to A and B
so it would fork and loop. The user got his mail account disabled. :)
On Tue, 14 Jun 2005, Matt Thompson wrote:
> OK, I'm kind of ashamed that I didn't know the answer to a question a
> friend posed me. It seems like something I should know, but I never
> thought about it. I also couldn't find the answer on Google, but that's
> probably due to noise on my searches.
> Namely, say you have two mailservers, A and B. In A, you have a .forward
> pointing to B, and in B a .forward to A. What occurs when you send mail
> to one?
> I'm sure this situation has some ARPANET-era jargon/USENET name that I
> don't know, and there is probably a paragraph about it in the Sendmail
> doorstop that I overlooked. Heck, maybe one of you even tried it once
> to see.
> Wondering away,
> The mayfly lives only one day, and sometimes it rains. - Geo. Carlin
> Matt Thompson -- http://ucsub.colorado.edu/~thompsma/
> 440 UCB, Boulder, CO 80309-0440
> JILA A510, 303-492-4662
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