We use SpamAssassin with Postfix on RedHat Linux in front of our Exchange server. I can either leave it alone or get as crazy as I want with the monitoring and updating. It mostly goes untouched for weeeks at a time. Postfix is a very secure, scalable MTA. You can do all kinds of crazy list checks, header checks, RBL's, sender restrictions, etc. You can use LDAP directly to verify recipient addresses, or you can just use a small perl script to grab addresses from your Exchange server at regular intervals throughout the day. Postfix combined with SpamAssassin makes a pretty tight "front door" to keep spam out. There are several options for combining Postfix, SpamAssassin, and Anti-Virus for even more garbage blocking power. Setting up a Linux MTA to use SpamAssassin is not for everyone, but it definitely works for us. -----Original Message----- From: Dee [mailto:deea@xxxxxxxx] Sent: Thursday, March 31, 2005 12:24 PM To: [ExchangeList] Subject: [exchangelist] Spam Blocker Suggestions http://www.MSExchange.org/ Current environment: Exchange 2003, Outlook XP, MailMarshal for Exchange It is taking way too much of my time to add additional filters, blocks, etc. for the daily new spam that is inundating our company's email. What do you all use and what would you suggest. I am looking for something I do not need to monitor for hours each day (i.e., false positives, new filters).