Abstract: A method for transmitting an encrypted message from a messaging server (106) to a handset (104) comprising the steps of receiving, at the messaging server (106) and from a sender computer (102), a message to be sent to the handset (104) and a handset identifier associated with the handset and determining that the handset is not registered with the messaging server (106) by determining that the handset identifier does not have an associated handset encryption key stored at the messaging server. The handset (104) is registered by sending a notification to the handset requesting registration, receiving back a handset encryption key associated with the handset identifier; and storing the handset encryption key against the handset identifier at the messaging server which is to be used to encrypt the received message before sending. Prior to registering the handset (104), intermediate encryption of the message may be employed to create an intermediate encrypted message to be stored at the messaging server.