Sieve forwarding loop destroys e-mail
mills at cc.umanitoba.ca
Mon Mar 31 08:38:45 EDT 2008
On Mon, Mar 31, 2008 at 02:04:29PM +0200, Alain Spineux wrote:
> On Mon, Mar 31, 2008 at 5:12 AM, Gary Mills <mills at cc.umanitoba.ca> wrote:
> > On Sun, Mar 30, 2008 at 02:27:29PM +0100, Alain Spineux wrote:
> > > On Mon, Mar 17, 2008 at 5:39 PM, Gary Mills <mills at cc.umanitoba.ca> wrote:
> > > > Once again, we had somebody use the sieve facility to redirect e-mail
> > > > back to the same mailbox and then go on vacation. This sets up a
> > > > forwarding loop which cyrus breaks by discarding the e-mail. During
> > > > this vacation, all of the person's e-mail disappeared.
> > >
> > > If you force a "keep" in your sieve script, the mail will be delivered
> > > at least once in
> > > the mailbox
> > It's perfectly valid to have nothing but a `forward' in a sieve
> > script. People do this all the time when they don't want to keep
> > a copy for themselves. Unfortunately, some also forward e-mail to
> > themselves, expecting that to work.
> sieve script is only a language.
> The language nor its interpreter nor its compiler dont need to be smart, because
> the script writer is supposed to be smart enough.
> If the user in unable to write such script, it must use a "sieve
> script manager", (application
> written by a smarter developer) that will help him generating well
> suited script.
There's no general solution to this problem in the script language,
even with a generator like we use. Again, that's because even the
generator can't tell what forwarding will cause a loop. I could, for
example, forward e-mail to my @fastmail.fm address, from where it
would come back to me. The generator could never know about my remote
In the simplest case, writing a sieve script to forward to yourself
causes the e-mail to disappear. The script writer could be considered
`smart' in expecting this to work. Calling the writer `stupid'
doesn't solve the problem.
-Gary Mills- -Unix Support- -U of M Academic Computing and Networking-
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