How PureMessage Combats Spam
PureMessage contains thousands of spam tests that analyze individual characteristics of each message. Each of these tests has a numerical weight. When a message is analyzed by PureMessage, the weights from all the spam tests that matched the message are added up and converted to a spam score that expresses the message's "spam probability".
By default, PureMessage checks for spam in messages that originate from outside the network, but it can also be configured to test messages originating within the local domain. If a message is found to have a spam probability of 50% or more, it is copied to the PureMessage quarantine. By default, PureMessage also delivers these messages, but alters the message's subject heading to show its spam probability.
PureMessage handles incoming email as follows:
- The mail transfer agent passes a message to PureMessage.
- PureMessage applies the policy filter to the message to test for viruses, spam indicators, or other message characteristics.
- Depending on the results of these tests, messages are either delivered to the original recipient, redirected or quarantined.
- PureMessage processes the quarantined messages. If quarantine digests are configured, end users can release desired messages from the quarantine. Other messages are usually automatically archived and deleted from the quarantine.