Re: [exim] Dealing with Yahoo mail RFC violations

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Autor: Todd Lyons
Data:  
Dla: Dean Brooks
CC: exim-users
Nowe tematy: Re: [exim] Per RCPT DATA reply (was: Dealing with Yahoo mail RFC violations)
Temat: Re: [exim] Dealing with Yahoo mail RFC violations
What about an (further) enhancement to esmtp to allow rejection of
individual recipients at smtp data time? Yeah, it adds increased
complexity on both the sending and receiving sides, but it solves the
problem nicely of "deliver oversized msg to everybody except $ISP".
For the sender, it already has the ability to handle queued delivery
of an email to one out of the entire list of recipients, so it's not
like it isn't already capable of that aspect. As far as the receiver,
it just needs to be able to say 4xx for a specific user (and the
sender needs to understand it of course).

Am I being too simplistic thinking that the addition of a new verb
could solve the per-user preferences problem nicely?

Regards....           Todd


On Wed, Jan 19, 2011 at 12:34 PM, Dean Brooks <dean@???> wrote:
> On Wed, Jan 19, 2011 at 08:16:35PM +0200, Stuart Gall wrote:
>
>> Ideally I would like to set a size limit for the yahoo.com domain so
>> that I immediately reject any mail > 5M with a yahoo recipient (and
>> possibly others throwing the baby out with the bath water etc)
>>
>> Is there a more sensible way to do this, or a better way all
>> together to deal with the problem.
>
> The difficult part in doing this with ACLs is that you wont often know
> the message size until SMTP DATA time, but by then your only choice
> would be to reject the entire message even if it meant rejecting all
> the other non-yahoo recipients.
>
> In my opinion, a better alternative might be to use a router to handle
> this.  This has the positive side effect of automatically meshing with
> normal RCPT verification in the event that the SIZE attribute was
> given in the MAIL command, not throwing out all the recipients because
> of one Yahoo recipient, and being easy to read without the use of
> extra variables.
>
> Something like this right before your remote_smtp router:
>
> limit_size:
>  driver = redirect
>  domains = yahoo.com
>  condition = ${if >{$message_size}{5M}}
>  allow_fail
>  data = :fail: message too large
>  fail_verify
>
> The only other side effect I can think of is that it will generate a
> bounce instead of an immediate rejection at SMTP time (if SIZE isn't
> given in the MAIL command and thus caught by RCPT verification).
>
> This isn't a bad thing though since this would only apply to your
> authenticated relay users and you generally dont want to do SMTP-time
> rejection to mail clients.  Some clients like Outlook will simply
> retry delivery over and over from the outbox when it gets an SMTP
> rejection.
>
> --
> Dean Brooks
> dean@???
>
> --
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--
Regards...      Todd
I seek the truth...it is only persistence in self-delusion and
ignorance that does harm.  -- Marcus Aurealius