A receptacle of a connector assembly , the connector assembly further comprising a plug mateable with the receptacle and accommodating an internal module therein, wherein: the receptacle comprises a shell made of metal and a cage formed of one or more metal plates, the shell being attachable to a case made of metal, the cage being mountable on a board arranged in the case; the cage has a receiving space and a plurality of enclosing plates ; the receiving space opens at a front end of the cage in a front-rear direction (X) and receives the internal module under a mated state where the plug and the receptacle are mated with each other; the enclosing plates include a cage rear plate , a cage top plate and two cage side plates ; the cage rear plate is located behind the receiving space in the front-rear direction; the cage top plate is located over the receiving space in an upper-lower direction (Z) perpendicular to the front-rear direction; the two cage side plates are located at opposite sides of the receiving space, respectively, in a lateral direction (Y) perpendicular to both the upper-lower direction and the front-rear direction; the cage is provided with a terminal made of metal and a contact portion made of metal; the contact portion is nearer to the cage rear plate than to the front end of the cage in the front-rear direction; and the contact portion has a spring portion and a contact point ; characterized in that the terminal extends downward from the cage rear plate; when the cage is mounted on the board and the shell is attached to the case, the shell covers the cage, the terminal is fixed to the board, and the spring portion presses the contact point against the shell. the receptacle comprises a shell made of metal and a cage formed of one or more metal plates, the shell being attachable to a case made of metal, the cage being mountable on a board arranged in the case; the cage has a receiving space and a plurality of enclosing plates ; the receiving space opens at a front end of the cage in a front-rear direction (X) and receives the internal module under a mated state where the plug and the receptacle are mated with each other; the enclosing plates include a cage rear plate , a cage top plate and two cage side plates ; the cage rear plate is located behind the receiving space in the front-rear direction; the cage top plate is located over the receiving space in an upper-lower direction (Z) perpendicular to the front-rear direction; the two cage side plates are located at opposite sides of the receiving space, respectively, in a lateral direction (Y) perpendicular to both the upper-lower direction and the front-rear direction; the cage is provided with a terminal made of metal and a contact portion made of metal; the contact portion is nearer to the cage rear plate than to the front end of the cage in the front-rear direction; and the contact portion has a spring portion and a contact point ; the terminal extends downward from the cage rear plate; when the cage is mounted on the board and the shell is attached to the case, the shell covers the cage, the terminal is fixed to the board, and the spring portion presses the contact point against the shell. <EOS>