A method is provided for localizing a prefix in a subject header field of an incoming electronic message. The method comprises receiving a value string of a subject header in an electronic message; identifying a system-generated prefix in the value string by parsing the value string and accessing a database storing a plurality of system-generated prefixes and a corresponding comparable local prefix for each of the plurality of system-generated prefixes; and converting the system-generated prefix to its corresponding comparable local prefix in the database.