Re: [exim] sender verify and greylisting

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Author: W B Hacker
Date:  
To: exim users
Subject: Re: [exim] sender verify and greylisting
Marten Lehmann wrote:

> Hello,
>
> our mailserver refused a certain email of a customer and when we tried
> to track down the problem, we noticed that the server of the server
> replied to our verification like this:
>
> mail from: <>
> 250 Ok
> rcpt to: test@???
> 450 <test@???>: Recipient address rejected: Greylisted for 300
> seconds (see http://...)
>
> Might this be the reason for the sender verify to fail? If yes, what can
> we do against it?
>
> Regards
> Marten
>


The above is only one of many false-positives.

'raw' sender verify should not be relied on as an all-or-nothing test.

The Exim MLM on sesame, for example fails sender verify at 'recipient', yet is
certainly on MY list of 'good guys'.

You need either a more sophisticated crafting of sender verification, a
'weighted' reaction to its return codes, or both.

Else use it only to add warning headers, not to reject.

Bill