Re: [exim] delaying inbound messages

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Author: Lena
Date:  
To: exim-users
Subject: Re: [exim] delaying inbound messages
> From: Jeff Lasman

> One
> of our users has suggested we delay all inbound messages on port 25 by three
> seconds to help eliminate spam.


> # Accept hosts who are polite enough to wait rather than just send, as spammers do


Exim already does that by default. Read description of the smtp_enforce_sync
main configuration option, then telnet to Exim, you'll see 3 seconds delay
between connection and SMTP banner. If a spambot or an abused proxy
tries to send HELO before the banner, Exim drops the connection.
Check how many messages in logs containing:

SMTP protocol synchronization error (input sent without waiting for greeting): rejected connection from

>   # Accept hosts who are polite enough to wait rather than just send, as spammers do
>   accept hosts = *
>          delay = 3s

>
>   # Deny hosts who don't wait      
>   deny message = Too quick on the draw - to unblock wait for helo/ehlo


This "deny" is never reached.