Hello, 

Graeme Fowler writes: 

> Getting back to the OP's question, and your answer: Dynastop isn't doing
> TXT lookups, because it's doing a different thing entirely. It might
> reduce the number of TXT lookups for a given query, but that's because
> it isn't doing DNS lookups at all.

Correct, there are no TXT lookups. 

DynaStop does a single realtime A ptr lookup.  The result is stored in a 
memory cache until expired.  Depending upon how active an IP address is, it 
may easily have several hundred hits from the cache as opposed to DNS 
lookups..  On a clustered mail server with multi DynaStop clients, one 
single lookup thoughout the entire cluster can be translated into a 
significant savings in resources and bandwith shared across the entire 
cluster.  On a single non-clustered system, there will be a still savings as 
DynaStop's cache will most likely outlive Exim's cache, depending on how 
active the IP address is. 

 --- 

DynaStop: Stopping spam one dynamic IP address at a time.
http://tanaya.net/DynaStop/

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