PROBLEM TO BE SOLVED: To enable a manager or the like to recognize fraudulence by instantaneously discovering the fraudulence, when the fraudulence utilizing electronic mail is carried out and to make.;SOLUTION: In a storage device, correct route information indicating the correct communication route of electronic mail is stored for each prescribed unit, beforehand. Then, electronic mail data which have passed through the prescribed part of a network are acquired. Actual route information indicating the communication route of the acquired electronic mail data is acquired. The correct route information stored beforehand and the acquired actual route information are compared to determine whether the correct route information and the actual route information match. When it is determined that the correct route information and the actual route information do not agree, a warning is outputted to the manager, or the like.;COPYRIGHT: (C)2009,JPO&INPIT
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