4. The method according to claim 1 , further comprising monitoring a performance of the first parser, and adjusting at least one of said at least one predefined rule in dependence on the monitoring.
1. A data processing method, comprising: receiving an electronically parseable document; and scanning the document according to at least one predefined rule to determine if the document is suspicious, wherein if the document is determined not to be suspicious, passing the document from a scanner to a first parser, and parsing the document with the first parser, and wherein if the document is determined to be suspicious, passing the document from the scanner to a second parser without passing the document from the scanner to the first parser, and parsing the document with the second parser, wherein the document is determined to be suspicious if the document includes a property that may cause a receiving computer system to fail, wherein the document is determined to be suspicious if the document comprises a well-formed document within a plurality of rules, but when the document is parsed, the document fails or slows down the receiving computer system to fail, and wherein the property includes at least one of a length of an attribute name, a number of an attribute per element, and a number of nested elements that exceeds a predetermined threshold.