Re: [Exim] verify = recipient/callout

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Szerző: Philip Hazel
Dátum:  
Címzett: Chris Edwards
CC: exim-users
Tárgy: Re: [Exim] verify = recipient/callout
On Mon, 12 May 2003, Chris Edwards wrote:

> The manual implies exim uses the actual sender address of the
> message, rather than just MAIL FROM: <>


<snip>

> However, on my system (exim4.14, solaris8) , the recipient callout simply
> does MAIL FROM: <> just like it does when verifying senders.


This is a bug in the manual. The code doesn't seem to have ever done
anything else.

> Thinking further, this is perhaps just as well. Suppose the target of the
> callout rejects the recipient perhaps because it has blacklisted the
> enevelope sender presented in MAIL FROM:
>
> Then, exim will presumably cache the fact this recipient is undeliverable
> and thus reject future valid senders without trying a new callout.
> So it would seem safer to verify recipients with MAIL FROM: <>


True. Also, what if the target host is itself using callouts to verify
the envelope sender? One wants to avoid callout cascades.

> In other words, the code seems right, the manual seems wrong.


I agree. Unfortunately, I have just "wrapped up" the 4.20 manual, and
I'm loath to unwrap it again at this late stage. I have therefore just
noted the change for the next edition, whenever that comes...


--
Philip Hazel            University of Cambridge Computing Service,
ph10@???      Cambridge, England. Phone: +44 1223 334714.