A method of notifying a user of an electronic communication system is disclosed. The method comprises the steps of: providing an electronic message including address data to an electronic communication process in execution within a computer system; identifying the address data within the provided electronic message; comparing address data within the provided electronic message with further address data stored on the computer within an address list; providing a notification to the user associated with the electronic message when a result of the comparison indicates that at least some of the identified address data is other than within the further address data, the notification other than a prompt to add the identified address data to the further address data.