Re: [exim] Bad SMTP commands?

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Author: Marc Perkel
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Subject: Re: [exim] Bad SMTP commands?


Marc Perkel wrote:
> Is there any way to count bad SMTP commands? I had someone tell me
> that a spam trick they use (not Exim) is to count bad smtp commands
> and drop after 4 of them.
>
>

Here's what I was told:

It's one of the things that you can do only with a stateful MTA; often
seen with open HTTP proxies (which will echo the HTTP commands in
addition to the SMTP commands). Zombies will also barge along without
paying attention to 5xx errors, so this is one of several ways that they
get disconnected. I'm working on a more sophisticated plugin which will
automatically disconnect servers that are not playing by the rules (e.g.
issuing RSET and retrying new addresses one after another).