A device comprising: a messaging application for receiving a sequence of messages directed to at least one destination user; non-volatile storage comprising one or more non-volatile storage devices for storing said messages, wherein the messages are user-consumable messages consisting of a number of consumed ones of said messages having been read, viewed or listened-to by the destination user, and a number of unconsumed ones of said messages not yet having been read, viewed or listened-to by the destination user, the messaging application being configured to keep a record of which of the user-consumable messages presently in the non-volatile storage are the consumed messages and which are the unconsumed messages; and an automatic message manager configured to implement different respective retention policies for the consumed messages and the unconsumed messages; the device being characterised in that: the retention policy for the consumed messages comprises automatically determining when the number of consumed messages exceeds a threshold for consumed messages, and in response automatically deleting at least one of the consumed messages from the non-volatile storage so as to bring the number of consumed messages back within the threshold for consumed messages, wherein the retention policies for the consumed and unconsumed messages are independent of one another, such that the number of consumed messages affects neither retention nor deletion of the unconsumed messages, and the number of unconsumed messages affects neither retention nor deletion of the consumed messages. a messaging application for receiving a sequence of messages directed to at least one destination user; non-volatile storage comprising one or more non-volatile storage devices for storing said messages, wherein the messages are user-consumable messages consisting of a number of consumed ones of said messages having been read, viewed or listened-to by the destination user, and a number of unconsumed ones of said messages not yet having been read, viewed or listened-to by the destination user, the messaging application being configured to keep a record of which of the user-consumable messages presently in the non-volatile storage are the consumed messages and which are the unconsumed messages; and an automatic message manager configured to implement different respective retention policies for the consumed messages and the unconsumed messages; the device being characterised in that: the retention policy for the consumed messages comprises automatically determining when the number of consumed messages exceeds a threshold for consumed messages, and in response automatically deleting at least one of the consumed messages from the non-volatile storage so as to bring the number of consumed messages back within the threshold for consumed messages, wherein the retention policies for the consumed and unconsumed messages are independent of one another, such that the number of consumed messages affects neither retention nor deletion of the unconsumed messages, and the number of unconsumed messages affects neither retention nor deletion of the consumed messages. the retention policy for the consumed messages comprises automatically determining when the number of consumed messages exceeds a threshold for consumed messages, and in response automatically deleting at least one of the consumed messages from the non-volatile storage so as to bring the number of consumed messages back within the threshold for consumed messages, wherein the retention policies for the consumed and unconsumed messages are independent of one another, such that the number of consumed messages affects neither retention nor deletion of the unconsumed messages, and the number of unconsumed messages affects neither retention nor deletion of the consumed messages.