On Fri, Nov 10, 2006 at 11:20:45AM -0000, Hill Ruyter wrote: > I understand all your points and they are all very valid > however should it be the case that someone be completely blocked purely on > the basis of a dynamic IP ?
Obviously any blocking based on information which doesn't include the contents of the mail in question is not an appropriate antispam measure because in general you can't tell whether a mail is spam or not until you've inspected its contents. Some people claim that presence or absence of a sending host on a `black list' is additional useful information for such a classifier, but based on my own observations I don't believe this. Generally a filter can determine (at some level of accuracy) whether something is spam, under a given user's definition, from its contents and the additional information that the mail passed through a host which was or was not on a `black list' is unlikely to change its decision very often. It is easy to see why this is so: a given user is unlikely to change their opinion of whether a mail they've received about, say, opportunities to purchase pharmaceutical products inexpensively, is desirable based on further information about the hosts through which it passed. Nevertheless there are lots of sites which do block mail based purely on `black lists' of one sort or another, as you have discovered. Sometimes it is possible to get the authors of the `black lists' to remove addresses from them, but generally if you depend on being able to exchange mail with people at sites run in that fashion all you can do is try to find another address through which to relay your mail or some other means to route around the idiocy. (As you will have seen from email to this list `black lists' are very popular among a certain sort of person and these people will strongly resist any argument against their use.) There is of course no guarantee that once you find such an address it won't itself be put on a `black list' and indeed one of the consequences of blocking on this basis is that the administrator who does so confers the power to block mail onto the authors of the `black lists' to exercise arbitrarily. If you choose to relay, of course, you are then depending on the competence etc. of the people running the relaying host, which is more-or-less beyond your control. Wherever you choose to run a mail server you will need to keep close watch on as many `black lists' as you can identify so that you can detect as soon as possible when some idiot decides to list you and take compensating action (and if you choose to relay, you trust the operators of the relay to do so themselves). -- ``The reason that the sun never set on the British Empire is that God wouldn't trust an Englishman in the dark.'' (Duncan Spaeth) -- ## List details at http://www.exim.org/mailman/listinfo/exim-users ## Exim details at http://www.exim.org/ ## Please use the Wiki with this list - http://www.exim.org/eximwiki/
