1.  Field of the Invention
The present invention relates to an electronic mail terminal device that transmits and receives information through electronic mail, and to a method of controlling such a device. 
2.  Description of the Related Art
In recent years, more and more network facsimile devices that are connected to a local area network or to the Internet and transmit and receive image information through electronic mail have been put into practical use.  The ITU-T recommendations have set the T.37 recommendation and the T.38 recommendation as the standards for those Internet facsimile devices. 
The ITU-T recommendation T. 37 specifies an electronic mail Internet facsimile communication method for exchanging image information through electronic mail via the Internet.  The ITU-T recommendation T. 38 specifies a real-time Internet facsimile communication method for exchanging real-time image information via the Internet in accordance with the Group-3 facsimile transmission procedure (the ITU-T recommendation T.30 procedure). 
In general, a network facsimile device has a function of exchanging image information via a public network, and a function of exchanging image information via a public network and the Internet through the electronic mail Internet facsimile communication function and the real-time Internet facsimile communication function. 
A network facsimile device having functions according to the recommendation T.37 makes an access to a mail server, in which the device has an account, at predetermined time intervals so as to fetch electronic mail addressed to the device. 
The above network facsimile device also has a power-saving function of restricting the power consumption while the device is in a stand-by state. 
Japanese Laid-Open Patent Application Nos.  10-91294 and 10-133835 both disclose such a power-saving function in a terminal device that performs electronic mail exchange. 
In the former reference, however, the mail server needs to have a function of notifying each client device of electronic mail reception.  In the latter reference, besides a network facsimile device, it is necessary to employ a printing device to print out received image information.  Because of this, the technique disclosed in this reference cannot be applied to a case where only a single network facsimile device is used.