Re: [Exim] Re: ANTISPAM reply-based unblock-sender-email (w…

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Autor: Giuliano Gavazzi
Data:  
A: William Thompson
CC: exim-users
Assumpte: Re: [Exim] Re: ANTISPAM reply-based unblock-sender-email (www/reply)
At 15:09 -0400 2003/05/02, William Thompson wrote:
[...]
>    # Reject HELOs that contain IP addresses unless we are a relay for
>    # them.
>    drop    !hosts = +relay_from_hosts
>        message = ${lookup \
>                mysql{select reject_reason \
>                  from eximconf.reject_messages \
>                  where reject_name='ip_helo'} \
>                {${expand:$value}} \
>               }
>        log_message = HELO is an IP
>        condition = ${if
>match{$sender_helo_name}{\N^\[?\d+\.\d+\.\d+\.\d+\]?$\N}{yes}{no}}

[...]

I think an IP as an HELO argument is within specs. At the same time I
think that any respectable mailserver would identify itself with a
name that resolves to its outgoing interface IP.
Presently I would accept an IP HELO unless it does not correspond to
the real IP of the peer (but my policy might change...).

I can confirm that a HELO check (also combined with a sender address
pattern check) can block most spam (even without RBLs), but it can be
the source of headaches with admins that cannot/want not to configure
their servers properly.

Giuliano