9. The computer program product of claim 1 , wherein identifying the document as a spam document, further comprises: determining for a document, first, second, and third most significant phrases present in the document, wherein the first phrase is the most significant phrase; determining, for the second most significant phrase, a number of the related phrases related to a second most significant phrase expected to be present in the document; determining, for the third most significant phrase, a number of the related phrases related to a third most significant phrase expected to be present in the document; for each of the first, second, and third most significant phrases, determining an actual number of related phrases present in the document; and responsive to the actual number of related phrases exceeding the expected number of related phrases for any of the first, second, or third most significant phases based on a threshold, identifying the document as a spam document.
9. The computer program product of claim 1 , wherein identifying the document as a spam document, further comprises: determining for a document, first, second, and third most significant phrases present in the document, wherein the first phrase is the most significant phrase; determining, for the second most significant phrase, a number of the related phrases related to a second most significant phrase expected to be present in the document; determining, for the third most significant phrase, a number of the related phrases related to a third most significant phrase expected to be present in the document; for each of the first, second, and third most significant phrases, determining an actual number of related phrases present in the document; and responsive to the actual number of related phrases exceeding the expected number of related phrases for any of the first, second, or third most significant phases based on a threshold, identifying the document as a spam document. 11. The computer program product of claim 9 , further comprising instructions that, when executed, cause the apparatus to: add the identified document to a spam list that includes a list of spam documents associated with the most significant phrase; and for each related phrase of the most significant phrase, add the identified document to a list of spam documents associated with the related phrase.