43. The method as recited in claim 30 , further comprising determining whether the document is related to a complementary document.
30. A method, comprising: receiving an image of a document; performing optical character recognition (OCR) on the image of the document; extracting an address of a sender of the document from the image based on the OCR; comparing the extracted address with content in a first database; identifying complementary textual information in a second database based on the address; and at least one of: extracting additional content from the image of the document; correcting OCR errors in the document using the complementary textual information, and normalizing data from the document prior to determining a validity of the document using at least one of the complementary textual information and predefined business rules.