The transaction filter on the HELO state works well if the announced name is the actual name. Spammers very often insert something else that changes faster than I can change my socks. This makes catching things like *adsl* not work all the time. If Mercury did an RDNS and the transaction could home in on the RDNS result then this would defeat the spammers. If when the RDNS finds that there is no name associated with the IP address, Mercury could insert, say "NULL" (as that is what gethostbyaddr returns), that could also be picked up by the transaction filter.
RDNS should be an option that can be turned on/off just in case there is too much of a performance hit for someone or is just not needed.
<p>The transaction filter on the HELO state works well if the announced name is the actual name.&nbsp; Spammers very often insert something else that changes faster than I can change my socks.&nbsp; This makes catching things like *adsl* not work all the time.&nbsp; If Mercury did an RDNS and the transaction could home in on the RDNS result then this would defeat the spammers.&nbsp; If when the RDNS finds that there is no name associated with the IP address, Mercury could insert, say "NULL" (as that is what gethostbyaddr returns), that could also be picked up by the transaction filter.</p><p>RDNS should be an option that can be turned on/off just in case there is too much of a performance hit for someone or is just not needed.
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