Part Four: External Hosts, Spam Probabilities

The fourth part of the policy script applies spam probabilities to those messages that have passed through the third part of the default policy filter, (External Hosts, Lists). The Manager screen shot shows where to edit spam probability rules and actions for messages from external hosts. A step-by-step description of this part of the policy is provided below.

Description:

Messages reaching this part of the policy script are from external hosts and have been prevously scanned for viruses and membership on various PureMessage lists (whitelists, blacklists, anti-spam opt-outs). Messages only reach the 'Spam Probabilities' section of the policy script because they haven't met the requirements for quarantining or sending. These messages now undergo specific scans testing for spam qualities, as follows:

  1. If the spam probability for the message is 50% or more:
    • An X-PerlMx-Spam header is added (or altered, if it already exists) that contains details of the scan, including the spam probability and the anti-spam rules violated by the message.
    • A copy of the message is written to the quarantine with the reason "Spam".
    • A mark is added to the message log indicating that the message is considered to be spam .
    • The subject header in the message is prefixed by the text PMX: and a # symbol for every 10% that the message's spam probability exceeds 50%.
    • The message is delivered.
    • Message processing stops.
  2. Otherwise:
    • An X-PerlMx-Spam header is added (or altered, if it already exists) that contains details of the scan, including the spam probability and the anti-spam rules violated by the message.
    • The message is delivered.
    • A mark is added to the message log indicating that the message indicating that it is legitimate mail.
    • Message processing stops.