
These solutions should work with most Unix (and POSIX) platforms. If you wish to use procmail or other applications to filter individual mail boxes see: Unix Client Side Spam Filters
MagicSpam – www.magicspam.com/

SpamAssassin - SpamAssassin.apache.org/ - see SpamAssassin Addons and Commercial Unix filters which use SpamAssassin (Reviews: 1)
RBLCheck - rblcheck.sourceforge.net
rblsmtpd - cr.yp.to/ucspi-tcp/rblsmtpd.html
BlackMail - www.jsm-net.demon.co.uk/blackmail/blackmail.html
Scanmail - www.scanmail-software.com/
spamGuard - www.enderunix.org/?tab=software&softname=spamguard
CRM114 - crm114.sourceforge.net/ - Bayes
Bogofilter - bogofilter.sourceforge.net/ - Bayes
Spamprobe - spamprobe.sourceforge.net/ - Bayes
MailStripper - www.eridani.co.uk/MailStripper/ - Linux, FreeBSD and Solaris
Expaminator - expaminator.sourceforge.net/ - Bayes
Bayesian Mail Filter - sourceforge.net/projects/bmf/ - Bayes
Distributed Checksum Clearinghouse - www.dcc-servers.net/dcc/ - mirrors: 1 - distributed
AGMSBayesianSpam - www.bebits.com/app/3055 - BeOS
DSpam - dspam.nuclearelephant.com/ - Bayes
Active SMTP - www.escom.com/asmtp.html
MailScanner - www.mailscanner.info/ - Postfix, sendmail, Exim or ZMailer
Kaspersky Anti-spam - www.kaspersky.com/antispamenterprise/
webfilt - www.pc-tools.net/unix/webfilt/ - web interface to server-side spam filters
Sendmail.com's Advanced Anti-Spam Filter - www.sendmail.com/
PreciseMail Anti-Spam Gateway - www.process.com/precisemail/precisemailds.htm
DSpam - dspam.nuclearelephant.com/
Spam Zapper - www.no-junkmail.com/Business.html
DSpam - dspam.nuclearelephant.com/ - Bayes, replacement MDA
Proofpoint Protection Server - www.proofpoint.com/products/pps.php - Solaris, Red Hat Linux
MagicSpam - www.magicspam.com/
Spamghetti - www.spamghetti.com/
MailBoss - www.mailboss.us/
PacketBL - freshmeat.net/projects/packetbl/ - netfilter client for Linux/BSD
SafeInternetEmail - www.cybersoft.com/cs_products/sie.php
rblsd - rblsd.sourceforge.net/
PureMessage - www.sophos.com/products/enterprise/email/security-and-control/unix/ (Reviews: 1)
CanIt - www.roaringpenguin.com/products/
Anti bad-mail SMTP wrapper - www.gentei.org/~yuuji/software/antibadmail/
Vorras Classifier - vorras.com/products/vorras_classifier/
SpamCannibal - spamcannibal.org/cannibal.cgi
Mail Avenger - www.mailavenger.org/
dbacl - dbacl.sourceforge.net/
OpenProtect - www.openprotect.com/ - KAV reseller bundle
OSBF-Lua - osbf-lua.luaforge.net/
Tagspam - copsewood.net/tagspam/
AISK (Artificial Intelligence Spam Killer) - sourceforge.net/projects/aisk/
Zimbra Collaboration Suite - www.zimbra.com/
Modular mimedefang-filter - www.xs4all.nl/~johnpc/mimedefang-modular/
Quick Spam Filter (QSF) - www.ivarch.com/programs/qsf/
MessagePartners - messagepartners.com/
Amavisd - www.ijs.si/software/amavisd/
DefenderMX - fsl.com/index.php/barricademx/defendermx
IceWarp Anti-Spam - www.icewarp.com/products/antispam/ (Reviews: 1)
COMDOM Antispam - www.comdomsoft.com/en/
Sendmail Mailstream Manager - www.sendmail.com/sm/solutions/inbound/ (Reviews: 1)
Kaspersky Anti-spam - www.kaspersky.com/kaspersky_anti-spam (Reviews: 1)
BitDefender Security for Mail Servers - www.bitdefender.com/PRODUCT-32-en--BitDefender-Security-for-Mail-Servers.html (Reviews: 1)
ESET Mail Security - www.eset.com/products/linux_mail.php
opensiqserver - www.bls.it/opensiqserver_en.php
SAGATOR - www.salstar.sk/sagator/
Clement - www.safe.ca/
Free Spam Filter - www.freespamfilter.org/
Fairly-Secure Anti-SPAM Gateway - www.flakshack.com/anti-spam/wiki/
Debian Anti-Spam Anti-Virus Gateway - www200.pair.com/mecham/spam/spamfilter20041003.html
Building an Anti-Spam solution on Sun - www.consorti.com/spam.html
Creating a Spamfilter Relay Server - geocities.com/scottlhenderson/spamfilter.html - Red Hat Linux
Per user configurable spam killer with Postfix and SpamAssassin - www.goblet.net/spamkill/
oSpam - omail.omnis.ch/ospam/
Blocking spam with Postfix and Amavis - www.stonehenge.com/merlyn/PerlJournal/col07.html
Implementing a spam and virus scanning mail server - www.spenneberg.com/postfix-amavisd-new.pdf
How To Install Postfix, Amavis, ClamAV, and Spamassassin on Debian Linux - www.fatofthelan.com/articles/articles.php?pid=22
Gentoo mailfiltering gateway guide - www.gentoo.org/doc/en/mailfilter-guide.xml
Configuring an Open Source Mail Gateway - freshmeat.net/articles/configuring-an-open-source-mail-gateway
Setting Up An Anti-Spam Gateway - www.geekcomix.com/cgi-bin/classnotes/wiki.pl?Setting_Up_An_Anti-SPAM_Gateway
How to install anti-spam gateways - www.howtoforge.com/howtos/email/antispam-antivirus
These mail servers for Unix have built-in spam control, and can replace your existing Sendmail, Postfix, qmail or Exim mail server.
XMail - www.xmailserver.org/
Postoffice SMTP server - www.pell.portland.or.us/~orc/Code/postoffice/