Re: Greylisting BCP
Jose-Marcio Martins da Cruz <[email protected]>
| Newsgroups | gmane.ietf.asrg |
|---|---|
| Message-ID | <[email protected]> |
Murray S. Kucherawy wrote: >> "greylisting is more expensive than not greylisting" >> >> Can you explain this? > > Put simply, any new filter has a cost to install, maintain, and operate. For greylisting there has to be a local store of sources that you've seen that get to bypass greylisting, so anything not on that list gets caught. That takes space, I/O, and processing time. So "expensive" in the resources sense. > You should take some care with this. Ressource usage varies a lot with different implementations : you'll find in memory chained lists, some RDBMS (e.g. MySQL) or ISAM/B-Tree/HASH (e.g. BerkeleyDB). Some implementations are smarter than others about ressources needes : e.g. how to expire old entries or how to aggregate them. And this makes a big difference on how expensive the filter is. Put simply, when talking about greylisting, expensive or not is more related to the implementation and to some tuning (e.g. delays) than to the method itself. I'm not even talking about poor programming practices... JM --