New York University Faculty of Arts and Science College of Arts and Science Graduate School of Arts and Science

Computing Resources

Spam Filtering


Email messages received on our mail servers are checked by Spamassassin. Suspected spam is tagged with an additional header which includes a spam score. CIMS users who receive emails locally on our servers can use this additional information to sort spam into separate folders. Our spam-tagged emails have an additional header that looks similar to this:

X-Spam-Score: 6.804 (******) DATE_MISSING,FROM_NO_LOWER,...

If you know how to setup filters on your mailer, you can ask your mailer to sort any mail with the X-Spam-Score: header into a separate folder. If your mailer does not have sorting capabilities, you can follow the instructions below to setup procmail to filter incoming emails for you. If you already have a .forward and/or a .procmailrc file, we assume you know what we are doing, and you can incoporate our sample recipes into your own setup.

Instructions for setting up procmail for spam filtering:

The are two ways to go about this. One is via the command line and the other is by using the Mail Configurator via your browser.
Using the Mail Configurator to set up procmail for spam filtering:
    The Mail Configurator can be used to configure procmail to filter your email, set up an autoresponse and to forward your email.
Using the command line to set up procmail for spam filtering:
  1. Copy the sample forward and procmailrc files into your home directory:
    cp /usr/local/lib/dots/.forward.sample ~/
    cp /usr/local/lib/dots/.procmailrc.sample ~/
    chmod 600 ~/.forward.sample ~/.procmailrc.sample
  2. [Optional] Go through .procmailrc.sample and modify it to suit your needs. It is well commented with instructions throughout. The default setup will sort messages with spam scores of at least 4 into the "spam" folder in your home directory. A spam score of 3 is the minimum that will be recorded on our mail servers, because the system seems to lose it's usefulness at this level. For example, while some messages with spam scores of between 3 and 4 are indeed spam, many are not (a legitimate attachment can trigger a score of greater than 3). However, our experience has been that almost all messages with spam scores higher than 4 are really spam. There are other sample recipes in the file that you may find useful. Among these are how to set up vacation to do automatic replies, and how to forward mail within procmail.
  3. Replace the string USERNAME in .forward.sample with your CIMS login name. Make sure you leave the '#' and '"' characters alone.
  4. Rename the files so that your filter will take effect.
    mv .procmailrc.sample .procmailrc
    mv .forward.sample .forward

That's it! Remember to look through your "spam" folder fairly regularly to look for false positives.