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Re: More sorbs blacklisting [signed]

Andreas John wrote:
> John Kelly wrote:
>> On Mon, 19 Jun 2006 20:06:04 +1000, "Charles Chambers [c]"
>> <cchamb2@qwest.net> wrote:
>>> my settings on SpamPal protecting my personal mail account are set to
>>> block according to *all* available blacklist sources ... my spam folder
>>> is fewer than a dozen pieces a week.
>> More than five is a bad week for me.  I use:
>> 1) strict DNS checks (matching forward/reverse)
> I understand that checking for the existence of a reverse mapping may be
> a clever thing, but the reason for forward/reverse matching is not
> obvious to me: Imagine a user who only has one public IP at his
> "all-in-one" mail-web-server. His reverse is www.mydomain.tld to make
> people with traceroute happy, but his mx is mx1.mydomain.tld. To get
> through your spamfilter, the reverse has to be changed to
> mx1.mydomain.tld - that looks not nice in the traceroute ...

Not if the check is that the reverse DNS for the MX has a matching A record.

 MX   mx1.example.com
 A    mx1.example.com  ->
 PTR     ->  www.example.com
 A    www.example.com  ->    ---> VALID

If the reverse for the MX's IP did not have a matching A record, that
would be an error and be blocked.

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