Abstract: An Email filtering system is disclosed which comprises: a user interface module is mounted on a server and allows access by one or more end-users; a database module containing one or more configuration options relating to the end-users, and which is connected to the interface and allows configuration options to be set and altered by the end-users; a SMTP listener module connected to the database module and to an incoming data stream containing Email messages, and whose behaviour is controlled on an Email by Email basis by the configuration options; a scanning engine module connected to the database module and to the SMTP listener module, so that the configuration options for the end-users modify the scanning engine module behaviour on an Email by Email basis; and a SMTP relay module connected to the database module and to the scanning engine module for SMTP Email delivery to end-user Email.