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Wikipedia Links
Complement Set Email Filtering Complement Set Filtering (CSF) is a method for filtering unsolicited bulk email (UBE or spam) The technique utilizes at least two email accounts: the primary account where spam and non-spam is received and secondary accounts that receive only spam. CSF calculates the set theoretic difference between the primary and secondary email sets (email accounts) and identifies email messages contained in both sets.
Implementation:
Email Filtering Email filtering is the processing of electronic mail to organise it according to specified criterion. Most often this refers to the automatic processing of incoming messages, but the term also applies to the intervention of human intelligence in addition to artificial intelligence, and to outgoing emails as well as those being received.