An image forming apparatus having a normal mode and a power-saving mode, said image forming apparatus comprising: a network interface unit (108, 330) for communication with an electronic mail server connectable to a communication network; a main control unit configured to perform a plurality of operations including a reception of an image data and an image formation based on said image data in said normal mode, wherein said main control unit is configured not to perform said reception of said image data and said image formation based on said image data in said power-saving mode; a sub control unit that performs an inquiry to said electronic mail server via said network interface unit (108, 330) in said power-saving mode about whether an electronic mail addressed to said image forming apparatus is stored in said electronic mail server, an image forming unit that forms an image on a recording medium, and a power control unit that performs power supply to at least said main control unit and said sub control unit, wherein said sub control unit is configured to operate with lower power consumption than said main control unit, wherein, when said sub control unit judges that an electronic mail addressed to said image forming apparatus is stored in said electronic mail server based on a result of said inquiry, said sub control unit acquires said electronic mail from said electronic mail server via said network interface unit (108, 330), wherein said sub control unit determines whether said electronic mail contains a print command information and determines whether said electronic mail contains a description of a status request, wherein, if said electronic mail contains a description of a status request, said sub control unit responds to said status request, wherein, after said sub control unit finishes responding to said status request, said sub control unit activates said main control unit to cause said image forming apparatus to shift from said power-saving mode to said normal mode, wherein, after said image forming apparatus is shifted from said power-saving mode to said normal mode, said main control unit acquires said electronic mail containing said print command information from said electronic mail server via said network interface unit (106, 330), and wherein said image forming unit forms an image on said recording medium according to an attachment file attached to said electronic mail acquired by said main control unit. a network interface unit (108, 330) for communication with an electronic mail server connectable to a communication network; a main control unit configured to perform a plurality of operations including a reception of an image data and an image formation based on said image data in said normal mode, wherein said main control unit is configured not to perform said reception of said image data and said image formation based on said image data in said power-saving mode; a sub control unit that performs an inquiry to said electronic mail server via said network interface unit (108, 330) in said power-saving mode about whether an electronic mail addressed to said image forming apparatus is stored in said electronic mail server, an image forming unit that forms an image on a recording medium, and a power control unit that performs power supply to at least said main control unit and said sub control unit, wherein said sub control unit is configured to operate with lower power consumption than said main control unit, wherein, when said sub control unit judges that an electronic mail addressed to said image forming apparatus is stored in said electronic mail server based on a result of said inquiry, said sub control unit acquires said electronic mail from said electronic mail server via said network interface unit (108, 330), wherein said sub control unit determines whether said electronic mail contains a print command information and determines whether said electronic mail contains a description of a status request, wherein, if said electronic mail contains a description of a status request, said sub control unit responds to said status request, wherein, after said sub control unit finishes responding to said status request, said sub control unit activates said main control unit to cause said image forming apparatus to shift from said power-saving mode to said normal mode, wherein, after said image forming apparatus is shifted from said power-saving mode to said normal mode, said main control unit acquires said electronic mail containing said print command information from said electronic mail server via said network interface unit (106, 330), and wherein said image forming unit forms an image on said recording medium according to an attachment file attached to said electronic mail acquired by said main control unit.