ClamSMTP: An SMTP Virus Filter

ClamSMTP is an SMTP filter that allows you to check for viruses using the ClamAV anti-virus software. It accepts SMTP connections and forwards the SMTP commands and responses to another SMTP server. The 'DATA' email body is intercepted and scanned before forwarding.

ClamSMTP aims to be lightweight, reliable, and simple rather than have a myriad of options. It's written in C without major dependencies. If you need more options then you could use something big like AMaViS which is written in PERL and can do almost anything.

I wrote this with the Postfix mail server in mind. Here's how to configure it as a Postfix Content Filter.

ClamSMTP can also be used as a transparent proxy to filter an entire network's SMTP traffic at the router.

Documentation

clamsmtpd(8): The man page.
clamsmtpd.conf(5): Man page for the config file.
Frequently Asked Questions

Notes

Tested on Linux, FreeBSD. And works on OpenBSD, NetBSD and Mac OS X as well.
ChangeLog
ClamAV: You'll need to have ScanMail support turned on in clamd.conf and have the clamd daemon running.
Here's a handy script for starting clamsmtpd as a specific user, stopping it etc...
Sample VirusAction script
Version 0.8 and higher use a config file instead of a bunch of command-line options.
If you need a flexible SMTP data filter take a look at ProxSMTP.

Mailing List

clamsmtp-users@lists.sourceforge.net
Subscribe/Unsubscribe | Archive

Downloads

Development:

You can get a snapshot of the source with git:

$ git clone git://thewalter.net/clamsmtp.git

Source code repository:
http://thewalter.net/git/cgit.cgi/clamsmtp/

Third Party Contributions

VirusAction Scripts
ClamSMTP Stats Package [Nagy Gergely]
Fedora/Redhat init script [Martynas Bieliauskas martynas@inet.lt]
Source RPMS [Martynas Bieliauskas martynas@inet.lt]
Mandrake startup scripts [Michael Burger]
RPM Spec File [Rubio Vaughan]
SuSE Linux startup scripts [Jens Jacobsen]
Setting up ASSP+ClamSMTP for FCS (scripts) [Ray Saunders, World Scout Bureau]