Collaborative digests

Collaborative spam detection networks such as Pyzor, Razor, and DCC rely on message digests. When a user identifies an email as spam, the system generates a unique hash of the message and shares it across the network. Incoming messages are then compared against the repository of spam hashes; if a hash matches, the message is flagged. The principle is straightforward: once one participant in the network identifies a spam wave, all other participants are immediately protected from the same messages.

Pyzor

Pyzor is an open-source collaborative spam detection system that uses collective intelligence to identify and filter spam. When users across the network mark messages as spam, Pyzor creates and shares their hashes; it also tracks messages users have reported as legitimate, reducing the risk that genuine mail is mistakenly flagged.

Configuration

Pyzor is configured through the SpamPyzor singleton (found in the WebUI under Settings › Spam Filter › Pyzor). It is enabled by default and points at the public Pyzor server public.pyzor.org with a five-second lookup timeout.

Relevant fields are:

• enable: enables or disables Pyzor.
• host: the Pyzor server hostname.
• port: the Pyzor server port.
• timeout: maximum time to wait for a response before the check is treated as failed.
• blockCount: minimum number of times a hash must appear in the Pyzor blocklist for the message to be considered.
• allowCount: minimum number of times a hash must appear in the Pyzor allowlist for the message to be considered.
• ratio: the ratio of blocklist hits to allowlist hits above which the message is treated as spam.

Example configuration matching the default public server:

{
  "enable": true,
  "host": "public.pyzor.org",
  "port": 24441,
  "timeout": "5s",
  "blockCount": 5,
  "allowCount": 10,
  "ratio": 0.2
}