# Presentation: 460423

## Dealing With Spam

- The email kind, not the Food product.

## 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

## 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

## 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

## 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

## 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

## 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”

## 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

## How Spam Assassin Works

- SpamAssassin uses two basic types of tests, regular expression tests and Real-time Black hole List tests

## 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

## 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

## 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

## 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

## 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”

## For More Information

- _[http://](http://computing.fnal.gov/email/spam)__[computing.fnal.gov](http://computing.fnal.gov/email/spam)__[/email/spam](http://computing.fnal.gov/email/spam)_/
- _[http://www.cauce.org/](http://www.cauce.org/)_
- _[http://spam.abuse.net/](http://spam.abuse.net/)_