Device, method, and computer readable medium for identifying fraudulent email using function terms

A fraudulent email decision method comprising:

• with respect to a newly received incoming email as a subject email, identifying an intention of the subject email from a body of the subject email by extracting one or more words from the body of the subject email, calculating for each extracted word a similarity between the extracted word and one or more function terms registered in advance, a function word expressing a reason a subject email was sent, and identifying the intention expressed by the function term similar to the extracted word, as the intention of the subject email;
• and
• deciding whether or not the subject email is a fraudulent email, from a relationship among the subject email, another incoming email received from a same sender as the sender of the subject email, and an identified intention of the subject email.

A non-transitory computer readable medium recorded with a fraudulent email decision program which causes a computer to execute:

• an intention identification process of, with respect to a newly received incoming email as a subject email, identifying an intention of the subject email from a body of the subject email by extracting one or more words from the body of the subject email, calculating for each extracted word a similarity between the extracted word and one or more function terms registered in advance, a function word expressing a reason a subject email was sent, and identifying the intention expressed by the function term similar to the extracted word, as the intention of the subject email;
• and
• an email decision process of deciding whether or not the subject email is a fraudulent email, from a relationship among the subject email, another incoming email received from a same sender as the sender of the subject email, and an intention, identified by the intention identification process, of the subject email.