A.P. Lawrence

PreciseMail Anti-Spam Gateway

Author: TonyLawrence
Date: Sat Mar 5 17:51:42 2005
Subject: PreciseMail Anti-Spam Gateway

This is a commercial product for spam filtering. They have an interactive demo and even a free trial, but annoyingly require filling out a sales contact form before you can get those things. You CAN read the features and benefits without trading info: http://www.process.com/precisemail/antispam.html
I did get the demo, and installed it as a proxy on the same Linux machine I have a mail server on. Although their instructions say that you need to run this on port 25 and rearrange your real mail server to run on some other port, in fact you can do it either way. I set it to listen on port 225, and just set the firewall to redirect 25 to that.

Probably the hardest part of this is configuring its web interface. While I know how to add something foreign like this to an existing webserver, I suspect at least a few admins would fail or need help. You don't absolutely need the web interface to get this running because you can manually edit its config file, but you do need the interface for convenient access to its views of quarantined files.

They say this is 98% effective with less than a .04% false positive rate and my testing supports that claim. It detected and blocked spam that Spamasassin did not. Users log into the web interface (authenticating either by LDAP, POP, IMAP or local password files) and can view their quarantined messages. They can "release" messages which will then go to the real mailserver, and whitelist specific senders if desired.

There is nice support for handling suspected spam - you can set a threshold where the message won't be quarantined but still gets tagged. That lets users define user agent filters to sort or tag those messages for review. For example, you could help cut down on mailbox clutter by leaving suspect messages to be reviewed after all other messages. User options also include:


# Receiving email notification summary of quarantined email twice daily
# Setting filter sensitivity
# Creating and modifying their own allow lists and block lists
# Opting out of filtering
# Forwarding missed spam or false positive messages to one inbox where the system administrator can review or send it to Process Software for analysis

Interestingly, they also offer a service based product: http://www.process.com/precisemail/pmfs/pmfs.html that has spam and virus filtering capability. This is similarly priced.

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