Re: [exim] How to avoid infinite autorespose loop ?

> > An autoresponder must always send its response, just like a bounce, with
> > an empty SMTP reverse-path.
> >
> > An autoresponder must always send its response _only_ to the address in
> > the reverse-path of the incoming message which triggers the mail, never
> > to any other address such as that found in From: or Reply-To: headers.
> > Obviously if the reverse-path is empty no message is sent.
>
> I'd agree with this, but you also need to defend against complete idiots
> at the other end. So I would add that you need to rate limit auto
> replies - for example where I have an autoreply it will only reply to a
> given address once per week. Even if it does loop I can cope with that
> loop rate.

And it could loop easily, e.g. by using fetchmail to get mails by POP
and bring them back on the way with SMTP, *guessing* the envelope sender,
and having them bounce. Don't think an empty envelope is enough.

> Rate limiting is done with the once options on the autoreply transports.

The Sieve "vacation" extension enforces that, too, plus it would never
reply to certain addresses that indicate mailing lists. I am sure someone
here :-) would appreciate if all autoresponders did that.

Michael