hello all, we're currently running Ralf Hildebrandt's "reject_unverified_sender" Postfix feature at MosCom, and initial results look interesting.
Quick overview: "reject_unverified_sender" is a neat feature. When smtpd receives the "Mail from:" right after HELO/EHLO, it queries its database as to whether the sender email is deliverable. There is an asynchronous process which probes the remote sender to update the database. e.g. spammers are fond of using forged email addresses, e.g. "[EMAIL PROTECTED]" etc. which change for every spam sent. Traditionally this is hard to block. However Postfix will query Hotmail.com as to whether such an account really exists. If it does not -- the mail is rejected. Postfix also caches "known good" sender e-mails, so for legal senders, there is virtually no performance slowdown. This is a very good feature which I think everyone should test. In conjunction with an RBL (e.g. orbs, monkeys, spamhaus) this feature of Postfix ought to stop 95%+ of all spam. You can get this feature in the latest snapshot of Postfix. The current 2.0.7 release doe *NOT* have it. --- Orlando Andico <[EMAIL PROTECTED]> Mosaic Communications, Inc. _ Philippine Linux Users Group. Web site and archives at http://plug.linux.org.ph To leave: send "unsubscribe" in the body to [EMAIL PROTECTED] Fully Searchable Archives With Friendly Web Interface at http://marc.free.net.ph To subscribe to the Linux Newbies' List: send "subscribe" in the body to [EMAIL PROTECTED]
