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From: Wolfgang Zeikat on 5 Aug 2010 08:05
Various sender domains use MX records like mail.spam.domain that point
to an IP that has a DSL PTR record, like 123-345-78-9.dsl.some.provid.er

Can I catch those using a table entry like
/\.dsl\.some\.provid\.er$/ result
?

Or would I have to use their IP or their A record, e.g. mail.spam.domain?

Regards,

wolfgang

From: Noel Jones on 5 Aug 2010 11:16
On 8/5/2010 7:05 AM, Wolfgang Zeikat wrote:
> Various sender domains use MX records like mail.spam.domain
> that point to an IP that has a DSL PTR record, like
> 123-345-78-9.dsl.some.provid.er
>
> Can I catch those using a table entry like
> /\.dsl\.some\.provid\.er$/ result
> ?
>
> Or would I have to use their IP or their A record, e.g.
> mail.spam.domain?
>
> Regards,
>
> wolfgang
>

check_sender_mx_access can match the MX records, which should
be a name, and the IP(s) that name resolves to; multiple
results are processed in pseudo-random order. Postfix does
not attempt to reverse-resolve the IP to a hostname.

So, if the spammer lists 2-2-3-1.dsl.some.provid.er as an MX
record, postfix can match it. If the spammer lists
mail.spammer.com as the MX, and that IP belongs to a dsl,
postfix can only match that by IP, not the name.

-- Noel Jones

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