Will Hill wrote: >Cnet is reporting that spammers have done the obvious and are making their >bots use ISP mailservers. Slashdot pointed to it: > >http://it.slashdot.org/article.pl?sid=05/02/02/2317243&tid=172&tid=111 > >They quote Linford of Spamhouse: > >/***************** >This will cause serious problems for the e-mail infrastructure, as it is >impractical to block mail with domain names from large ISPs. > I don't see this as a big problem to businesses - we use spamassasin but an RBL hit only adds 1.0 to the spam score - not matter how many RBLs fail the message. We accept and flag anything with a score of 4.9 and delete anything with a score of greater than 8.0 - this after several months of testing. We don't see a lot of mail (20 users and only about 5,000 emails per day, 95% of which are junk) but the false positive rate is way lower than 1% - I'd guess it's around 0.1% and most of the false detections are junk from friends - not commercial messages ... and this is with a bunch of customers in Korea! One thing that helps is that we've set up our own spamassasin rules to flag words and technical terms that our customers use. I have been using the same email addresses for about ten years - several of which are posted in plain text on web pages.
We have about 4 different blacklists, and use SPF and tarpitting but most spam is thrown out based on content, not RBL hits - Bayes filtering is nice but writing your own custom rules for spamassasin makes a big difference - especially if you subtract from the score when you find words that you're interested in ... like our product names etc. I also spambait usenet and dump anything that comes in with a spambait address anywhere in the headers. We also filter viruses at the mail server, both incoming and outgoing - virus definitions are updated every hour. I'd agree that the spam volume is rising - but I don't think that it's a big deal commercially - it's the home users who are getting hosed by this, not the corporate users. -- 'Martyrdom' is the only way a person can become famous without ability. -- George Bernard Shaw
