In apparatus for the successive discharge and conveyance, along a conveying path, of items of mail from a stack by a continuously driven conveying device and an externally controllable removal member arranged to transport successive items from the stack to the region of action of the conveying device, the desired spacing between successive items is established by the provision of a first sensing unit disposed between the stack and the conveying device to define a first measuring path extending along the conveying path and to provide an output signal indicative of the length of the portion of the first measuring path traversed by the leading edge of an item presently being conveyed by the removal device, a second sensing unit disposed downstream of the first sensing unit, along the conveying path, to define a second measuring path offset from the first measuring path, along the conveying path, by a distance corresponding to the desired spacing between successive items, and to provide an output signal indicative of the length of the portion of the second measuring path traversed by the leading edge or trailing edge of an item being conveyed by the conveying device, and a control member connected to place the removal device into operation upon production of output signals indicating that the length of the portion of the second measuring path traversed by the leading or trailing edge of an item is equal to the length of the portion of the first measuring path traversed by the leading edge of the immediately following item.