Dealing With Spam

1. Dealing With Spam The email kind, not the Food product.

2. What is Spam? • Unwanted/unrequested commercial email • Sometimes for questionable, possibly illegal goods or services • On large scale is a significant waste of time and resources

3. What isn’t Spam? • Are viruses spam? • Are phishing scams spam? • Not really, they are a different kind of problem, but often spam filtering techniques will catch these emails as well

4. How to Avoid Spam • Most spammers these day get email addresses via web crawlers • Avoid putting your email address on web pages • Beware web based message boards and web based mail list archives • New software should be smart enough to obscure email addresses, but check first

5. Avoiding Spam • If you need to list your email address in public, make it hard for machines to read • Spell out parts, such as “kevin AT fnal.gov” instead of using an ‘@’ • Create a .jpg or .gif image of your email address

6. Spam Filtering At Fermilab • On the central email servers at Fermilab, all email from outside the lab passes through our spam filtering servers • These servers pass all email through a program called SpamAssassin • This inserts hidden headers with a “spam score” that email programs or other servers can filter on

7. Spam Filtering at Fermilab • No email is blocked on the email gateways for spam content • The IMAP servers by default deliver email with a spam score of 5 or higher to a folder called “Tagged Spam”

8. Tagged Spam • If you don’t see your ‘Tagged Spam’ folder, you may have to subscribe to it • In Netscape, Mozilla, or Thunderbird, go to the File menu and select Subscribe • You can also access it via the Webmail interface • Don’t forget to delete old spam occasionally to save quota space

9. How Spam Assassin Works • SpamAssassin uses two basic types of tests, regular expression tests and Real-time Black hole List tests

10. Regular Expression Tests • Test for known spam words or phrases • “Get Rich Quick” • “$$$$$” • “From: big____@hotmail.com” • Other sorts of tests like faking email from Outlook instead of spam generating software • Subtle things like too many html color changes

11. Realtime Blackhole Lists • Test the “received” headers to identify machines the message passed through • Checks for • Spammer owned machines • Poorly configured email servers • Known hacked machines • Spam Assassin does not block on these, but “hits” == more spam score

12. Other Ways to Fight Spam • Netscape/Mozilla/Thunderbird have Adaptive spam filtering • The email client looks at the words in email you mark spam/not spam and learns how to classify better • Its important to correct mistakes, just click the “Junk/Not Junk” button on the toolbar

13. Teaching Mail Filters • I find it easier to configure Thunderbird to move its Junk to a separate folder • This way I only have to look for spam in my inbox, and non-spam in my Junk folder • Less brain overhead than checking the little junk icon on every message

14. Other Mail Filters • If you see regular spams with a certain sender, subject or recipient, most modern mail clients have easy to use filtering built in • Mail filters are now available on the Fermi IMAP servers as well • To edit your IMAP filters, log on to the webmail interface, click on “Options”, then “Mail Filters”

15. For More Information • http://computing.fnal.gov/email/spam/ • http://www.cauce.org/ • http://spam.abuse.net/