Re: [Exim] Re: Bagle, unqualified HELO, time delays

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Author: Edgar Lovecraft
Date:  
To: exim-users
Subject: Re: [Exim] Re: Bagle, unqualified HELO, time delays
Fred Viles wrote:
>

..[snip]...
>
> IMO, artificial delays should be introduced into the SMTP session *only*
> if there is already good reason to suspect that the sender is not
> legitimate. Then the benefit outweighs the infrastructure cost (IMHO).
>

I agree with that statement, that is how I do things, as examples:
if verified helo == yes, then no delay,
if connecting IP == DUL, then delay xx seconds
if connecting IP == null rDNS, then delay xx seconds
so on and so forth, doing things in this type of manner does not
penalize those who have properly configured servers, and in effect
gives them a 'preferred connection status' and we return all responses
without delay. I also think that this type of approach helps to encourage
a 'properly' configured mail server on the other end.
As an addition, I also keep track off why any IP connection was delayed
during the SMTP conversation so that I can 'help educate' the admin at the
other side. So far, it works very well (even the education part of it :)
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