Re: [exim] Use of hashes to fix forwarding

On Wed, 2 Feb 2005, Peter Bowyer wrote:

> On Wed, 02 Feb 2005 10:48:22 -0500, Marc Sherman <msherman@???> wrote:
> > Dennis Davis wrote:
> > >
> > > Certainly at least one other UK University has been successfully running a
> > > similar scheme for over a year. Although I believe they don't use a hash
> > > signature. Instead they include a simple header. Apparently some external
> > > stuff does break, in particular eBay alerts.
> >
> > Could you please give some more details of this breakage with eBay alerts?
>
> Some of the mails eBay sends are forged to look like they came from
> another eBay member - if you ask a question about an item, for
> example. They don't just forge the reply-to (which would be fine), or
> the From: header (which might also be OK), they forge the envelope
> sender as well. Which isn't.
>
> So if one of your users asks a question about an eBay item which
> another of your users is selling, you get incoming mail with your
> domain in the envelope sender.

While I can't give any other examples, it being a very long time since I
considered implementing a rule like this, eBay isn't the only service that
does this sort of thing.

I'm surprised in implementing this rule you haven't had complaints.

As I think Dennis mentioned, you'll also need to make sure that your users
offsite don't sent email apparently from their institutional address via
an ISP: they must use your own submission service.

Jethro.

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Jethro R Binks
Computing Officer, IT Services
University Of Strathclyde, Glasgow, UK