Re: help with how to drop connection on syntax error

Andrew C Aitchison via Exim-users <[email protected]> Wed, 1 Jul 2026 07:16:19 +0100 (BST)

Newsgroups	gmane.mail.exim.user
Message-ID	<[email protected]>

On Tue, 30 Jun 2026, v via Exim-users wrote:

> I was hoping someone here could help me with this.  How can Imake
> exim DROP the connection faster, in response to being dos flooded
> with gibberish.  How, and where, can I make it DROP on first syntax
> error, instead of it sending back countless "500 unrecognized
> command" or "501 NUL characters are not allowed in SMTP commands"
> and what not, then sitting there witting for smtp_receive_timeout.

According to my reading of the spec, unless you have set
   smtp_max_unknown_commands
exim should DROP the connection after 3 unknowm comamds,
so I am not sure why it is allowing countless errors.

-- 
Andrew C. Aitchison                      Kendal, UK
                    [email protected]

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