[Exim] Re: about SMTP callback.

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Auteur: Marc MERLIN
Datum:  
Aan: Philip Hazel
CC: exim-users
Onderwerp: [Exim] Re: about SMTP callback.
[moving to exim-users list]

On Thu, Nov 29, 2001 at 08:59:22AM +0000, Philip Hazel wrote:
> On Wed, 28 Nov 2001, Marc MERLIN wrote:
>
> > exim 3.x doesn't support caching of SMTP callback info. I'm hoping that exim
> > 4 does. Philip, can you confirm or deny?
>
> Deny.


Ok thanks.

> Oh, I see that caching callout information is already on the Exim 4 Wish
> List.


Good :-)

> I guess it's something to think about for the future, but all this
> callback stuff is still relatively new and I'm still learning how it is
> used and what is needed.


Well, being a heavy user of SMTP callback, I can tell you the
problems/features needed:

- caching of positive callbacks (by far #1)
(I do not really want caching of negative results, as I'd rather have
people who just fixed their mail server be able to send right away)

- Being able to do an additional callback on the domain for a special
address (like postmaster@ and optionally abuse@). My patch implements that
by piggybacking on top of the current callback, it does a RSET, a new mail
from: <>, and tries the 2nd address.

- Some way to optionally not do SMTP callback if there is a certain header
line in the message

The 2nd one is important if we don't want people on mailing lists to be
flooded with SMTP callbacks every time they post to a list.
The way this would work is that if the list server runs exim with SMTP
callbacks, it would check the mails as they are posted, add a header saying
that the header from has been checked, and rebroadcast to the list
subscribers

List subscribers would then be encouraged to not do callbacks if the special
header is there.

Marc
-- 
Microsoft is to operating systems & security ....
                                      .... what McDonalds is to gourmet cooking


Home page: http://marc.merlins.org/ | Finger marc_f@??? for PGP key