Greylisting.Org > Implementations

Generic approaches


Smtpwrap, created by Brian Gough is the first greylisting implementation I have yet seen that does not require any specific MTA deamon. For more information see his page at:

SpamCage from is a generic SMTP proxy able to work a wide range of MTAs (qmail, postfix, sendmail etc.). It is available for testing here: (this link no longer works!)

Spey developed by David Given is a SMTP proxy designed to sit in front of an existing MTA. It is written in C++ (potentially far more effective than any scripting based implementations) and uses SQLite as database backend. It can be found here:

ASSP is an Open source SMTP proxy that with many advanced features runs under *nix and Windows operating systems, it also contains greaylisting functionality:

ITEISA has developed a new SMTP proxy, the Hermes Antispam Proxy. It sports effective C++ code with a SQLite (also very efficient) database backend. Some of its features includes STARTTLS and SMTP-AUTH:

eWall, a Server Side Solutions project, is programmable gateway for any mail server. With very few configuration changes it supports greylisting directly:

MIMEDefang, a framework for filtering e-mail, supports greylisting:

CanIt from Roaring Penguin, which is the commercial framework for filtering e-mail, also supports greylisting. Homepage:

SMTP Preprocessor, by Sergey Merzlikin, which works as a pass-through filtering server for any corporate mail server, now also (from version v.1.08) supports greylisting. Info:

The Secure Messaging Server/Appliance from ITAnetworks, which basically works like a firewall for all SMTP traffic going to/from the network, supports greylisting. The product is designed to effectively stop virusses and spam mail. Info:

Alligate SMTP Gateway is an Antispam gateway designed to reduce the load on your mail server by prevent spam from reaching it. It supports greylisting and supports any MTAs. More info:

Gross is a high performance greylisting server that supports DNSBL lookups and multiple MTAs (Sun Java System Messaging Server, Postfix, Sendmail and Exim). Info:

eWall is a programable email gateway from Server Side Solutions. Amongst many other antispam measures it also supports greylisting. Information:

SpamCheetah is a OpenBSD based liveCD distrubition, which includes features such as greylisting, load balancing and automatic failover:

BarricadeMX (aka smtpf) from SnertSoft is a SMTP filtering proxy that supports a form of greylisting called "Enhanced grey-listing": A reseller can be found here: