Abstract: The disclosure relates to ensuring wanted electronic messages are reliably delivered to recipients by distinguishing between wanted, authenticated messages and other messages. Also, it provides for automatically compiling a datastore with senders of wanted inbound electronic communications. This is done by entering part entries into the datastore as messages are send outbound, and completing the entry as messages are sent inbound or with reference to an external datasource. The whitelist is automatically created and accurately populated and maintained without the need for any human involvement making it self training. This enables mass automation for whitelist generation and maintenance, and enables consistent, scalable deployment across any and all organisations to ensure accuracy in classification of wanted message senders.