To efficiently use the storing areas of a electronic mail server and electronic mail clients and, in addition, to preserve electronic mails for a long period.

An electronic mail keeping system is composed of plural electronic mail clients 2a-2x connected to a network and an electronic mail server 1 and the server 1 has a large-capacity storage device 3 loaded with a temporary storage device and plural portable large-capacity storing media, records an electronic mail received through the network in an area preassigned to its destination in the temporary storage device, and can record the electronic main recorded in the temporary storage device in the storing media of the storage device 3. The server 1 also deletes the electronic mail from the temporary storage device.