Re: [Exim] Callout verification

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Author: Wakko Warner
Date:  
To: Matthew Byng-Maddick
CC: exim-users
Subject: Re: [Exim] Callout verification
> > such as re-presenting the MAIL TO with a valid sender if you want to
> > (or configurable to just use the alternative valid sender in the first
> > case, might make more sense).
>
> What happens if that machine tries to do a callout on the now "valid"
> sender?


I've been watching the thread. In this case the burden I feel would be on
the person doing the original call out.
Here's how I see how it should happen:
<< smtp from client
<< mail from:<client@here>
>> ok

<< rcpt to:<recipient@there>
    ** Do a callout here
    >> smtp to client's server
    >> mail from:<>
    << No address found
    >> reset
    << ok
    >> mail from:<postmaster@there>
    << ok
    >> rcpt to:<client@here>
        ** they do a callout here for postmaster
        << smtp from client's server back to "there"
        << mail from:<postmaster@here>
        >> ok
        << rcpt to:<postmaster@there>
            ** Unconditionally accept for postmaster or
            ** immediate reject.  No call out.
        >> ok
    << call out ok, continue
    >> quit

>> call out ok, continue

<< data
>> give me the rest ending with a single dot.

<< ...
>> ok

<< quit
>> ok and closing.


If allowed to use any address than a local address that does callbacks, then
there would be a loop. If they don't do call backs, I don't see how a loop
could possibly happen.

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