SMRazor

This is a Milter for Sendmail 8.12 that checks mail messages using razor-check and rejects ones that are found in the razor database.

It is extremely simple, it just pipes the mail message to a forked off version of razor-check and looks at the return value. Since sendmail sends messages with CRLF at the end of each line and razor-check doesn't like that, it does strip off the CR.

I run it on FreeBSD using Vipul's Razor 2.14 and Sendmail 8.12.3. Vipul submitted a patch that gets it to compile on Linux which I've incorporated. Jamie Orzechowsk got in running on Redhat 7.2 and helped me kill some bugs, so it should work nicely on Redhat 7.2. Bobby Rose has helped me get it working on Solaris 8.

Changes

0.2.1

• Changed the default behavior to not reject spam. It just adds the X-SMRazor: SPAM header.
• Fixed a bug reported by Sven, where it would crash anytime there was no subject header in the email.

0.2.0

• Changed the header that is added to each email to 'X-SMRazor: ok' or 'X-SMRazor: SPAM' depending on whether it is ok or spam.

0.1.0

• Use GNU configure to generate makefile.
• If razor-check exits with anything other than 0, we accept the message.

0.0.6

• Fixed a bug where it got an Invalid Seek error in a couple of different message situations.
• Added some debug facilities and a bunch of debug messages.
• Upped the razor-check timeout to 30 seconds and made it a define.
• Changed the error file name to /tmp/smrazor.err.
• Adjusted the makefile to work with GNU make.

0.0.2

• Now compiles on Linux.

0.0.1

• Initial release.

Installation

To use it with Sendmail 8.12 you must have compiled Sendmail with Milter support. To do that, you add this to your site.config.m4 file when compiling Sendmail:

APPENDDEF(`conf_libmilter_ENVDEF', `-DMILTER')
APPENDDEF(`conf_sendmail_ENVDEF', `-DMILTER')

Then you add this to your .mc file that you use to build your sendmail.cf file:

INPUT_MAIL_FILTER(`smrazor', `S=local:/var/run/f1.sock')

Then you need to run 'smrazor' as root. It is a daemon that does not fork itself. I do this:

./smrazor -p local:/var/run/f1.sock&

Now every message that comes into sendmail will be checked with razor-check. If it is rejected, it logs the 'From' and 'Subject' lines to '/tmp/razored.log'.

It also spits out debug messages from razor-check to '/tmp/razor.err'.

It always accepts any messages that are to users who start with 'spam'. This is because I route those emails using procmail to razor-report.

Most of this stuff is hardcoded into the program, but it is pretty simple to work with, so have at it.

Info

More information on Milter is at:
http://www.sendmail.com/partner/resources/development/milter_api
and
http://www.milter.org

More information or Vipul's Razor is at:
http://razor.sourceforge.net

Feel free to email me about it at:
razor@sapros.com