Re: [Exim] Callout timeouts: opinions sought

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Author: Nigel Metheringham
To: Alan J. Flavell
CC: Exim users list
Subject: Re: [Exim] Callout timeouts: opinions sought
On Fri, 2004-08-20 at 14:46, Alan J. Flavell wrote:
> I'm convinced that I've seen an MTA respond OK to MAIL FROM:<> , and
> then respond to the RCPT TO with a diagnostic which rejected the null
> sender address. Yup, here's an example:
> [...] sender verify fail for <TacK@???>: response to "RCPT
> TO:<TacK@???>" from [] was: 550 5.7.1
> Remitente vacio no permitido. Empty sender not allowed.
> It's uncommon, but it does happen.

That might well happen if someone forges a message from (say) the
exim-users list (using the list address as envelope sender - since the
list sends no mail itself it is configured to reject bounce messages),
or from people using one-time or keyed sender addresses - David
Woodhouse is, I believe, one person doing that.

[ Nigel Metheringham           Nigel.Metheringham@??? ]
[ - Comments in this message are my own and not ITO opinion/policy - ]