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Spam Control and Deterrence

What to do about Spam

  • We do make best effort to prevent spam sent to you from being delivered
  • There's not much we can do to prevent attempts to send it to you; we can't follow up and investigate individual messages.
  • There's a lot more information at the OIT Spam information page

Greylisting and blacklists

We run the OpenBSD spamd service to prevent or delay message delivery from suspect servers. In addition, systems which attempt to send messages to nonexistent accounts or defunct physics hostnames are temporarily blacklisted.

You can view a list of messages which were blocked or greylisted (delayed) on your MyPhys page. Delayed messages should normally arrive within about a half hour (although to some extent this will depend on the sending mail system), and once a message has been delivered, future messages from that source will have no delay.

Spam Filtering

We also run the SpamAssassin filter on all incoming messages to our mail system. SpamAssassin simply assigns each message a “score”, based on the content.

  • Messages with a score of 5 or less are left alone
  • Messages with a score between 5 and 10 have the text SPAM added to their subject line before being delivered.
  • Messages with a score over 10 are rejected (our system refuses to deliver them to you and the sender receives a bounce message).

Custom Filters

You can change settings within your account to take further action based on the spamassassin score, such as move messages to a different folder, or even delete them completely.

These settings are made within the Physics webmail system. As an example, let's say you want to filter those messages with scores with 6 or higher, so they are placed into a separate folder instead of your INBOX.

  • After logging in to the webmail system, click on Filters
  • Click on Add a New Rule
  • Under Condition change the first drop-down box which says To: or Cc to X-Spam-Level
  • In the text box after contains enter

    (that is, 6 stars)

  • Under Action choose Move message into and select a folder name as the destination.
  • Under Additional actions, check STOP: If this rule matches, do not check any rules after it.
  • Click Add New Rule

Understanding SpamAssassin Scores

You can see the set of rules which triggered a spam tag for a particular message in the header “X-Spam-Status”, and the list of SpamAssassin's default scores can be found here: Spamassassin default scores

computing/accounts/email/spam.txt · Last modified: 2011/01/14 18:36 by allan