lac wrote: >--- Tracy <[EMAIL PROTECTED]> wrote: > > >>I can't speak for anyone else, but I've found that denying service to >>"dynamic" addresses (based on RDNS patterns) to be a very effective tool >>for reducing both spam and virus traffic. Since most (not all, as has been >>pointed out here in the past) dynamic addressed machines are covered by >>terms of service or acceptable use policies that prohibit the running of >>servers, a case can be made that these machines should not be sending mail >>directly to mail servers (other than the ISP responsible for their >>connectivity). >> >>And, of course, if there are specific machines that are running mail >>servers, they can avoid such a block in two ways: >> >>1) Getting a static IP address from their provider so that you can >>whitelist the address >>2) Getting "non-generic" RDNS assigned by their provider >> >> >[...] > >Of course 1. and 2. are not feasible for about 99% of broadband users who >want to run a legitimate mail server. Static address and RDNS is out of the >question (an ISP usually charges a busisness rate for this) > >-Lac > >
I've been grey listing suspect servers, returning a 4xx error in a pre-data filter on the first try, then letting it through on the next, assuming enough time has passed. This does complicate things, as you'll need to track the senders email address and IP address, and the rcpt(s) address in a database -- but it seems to be working well with few false positives. It can potentially delay a good amount of mail however, depending on how you decide what's suspect or not - and gets even more complicated if you have any backup SMTP servers. - To unsubscribe from this list: send the line "unsubscribe xmail" in the body of a message to [EMAIL PROTECTED] For general help: send the line "help" in the body of a message to [EMAIL PROTECTED]
