Multiple modules are provided, each one of which is configured to analyze email messages in a different manner than other ones of the modules. For a received email message, a plurality of the modules are used to determine one or more module outputs indicative of a level of sameness of the received email message with one or more prior email messages. At least two of the modules being used are each assigned a non-zero weight indicative of the performance level of the module. An overall level of sameness of the received email message with one or more prior email messages is determined by combining the module outputs of at least two of the plurality of modules using the non-zero weights assigned to the modules.