An office mailing machine for printing mail items comprising: - a frame with an opening for manually inserting and removing the mail item; - a print head supported by a carriage sliding in a longitudinal direction for printing the mail item, - an item transverse moving mechanism for moving the mail item in a direction transverse to the longitudinal direction, the item transverse moving mechanism comprising a twin train of pivoting rise and descent lever arms (72a, 72b) each acting on a one-way cogwheel (75a, 75b) configured to drive in rotation an axle shaft and to lower item bearing stops (78c, 78d) by moving around fixed (77a, 77b) and free pulleys (79a, 79b) item indexing belts (78a, 78b) bearing said item bearing stops; - an item registration arrangement for positioning the mail item and maintaining it in a perpendicular direction at a constant gap from the print head, the item registration arrangement comprising a registration plate with a right angle corner and a spring-loaded pressing mechanism pivoting around a rod and having a pressing plate and two pressing end parts (81a, 81b), the pressing plate pushing the mail item against the registration plate in opposition to springs (87a, 87b); - the print head supporting carriage comprising three cam surfaces (23a, 23b, 23c) that respectively cooperate with cam surfaces (73a, 73b) of said rise and descent lever arms and cam surfaces (83a, 83b) of said pressing end parts; - an electronic control module for starting and performing a print cycle; and - a single drive mechanism connected to the print head supporting carriage for simultaneously: (a) moving the carriage back-and-forth along the longitudinal direction; (b) indexing the mail item by controlling the item transverse moving mechanism and (c) registering the mail item during printing by controlling the item registration arrangement. - a frame with an opening for manually inserting and removing the mail item; - a print head supported by a carriage sliding in a longitudinal direction for printing the mail item, - an item transverse moving mechanism for moving the mail item in a direction transverse to the longitudinal direction, the item transverse moving mechanism comprising a twin train of pivoting rise and descent lever arms (72a, 72b) each acting on a one-way cogwheel (75a, 75b) configured to drive in rotation an axle shaft and to lower item bearing stops (78c, 78d) by moving around fixed (77a, 77b) and free pulleys (79a, 79b) item indexing belts (78a, 78b) bearing said item bearing stops; - an item registration arrangement for positioning the mail item and maintaining it in a perpendicular direction at a constant gap from the print head, the item registration arrangement comprising a registration plate with a right angle corner and a spring-loaded pressing mechanism pivoting around a rod and having a pressing plate and two pressing end parts (81a, 81b), the pressing plate pushing the mail item against the registration plate in opposition to springs (87a, 87b); - the print head supporting carriage comprising three cam surfaces (23a, 23b, 23c) that respectively cooperate with cam surfaces (73a, 73b) of said rise and descent lever arms and cam surfaces (83a, 83b) of said pressing end parts; - an electronic control module for starting and performing a print cycle; and - a single drive mechanism connected to the print head supporting carriage for simultaneously: (a) moving the carriage back-and-forth along the longitudinal direction; (b) indexing the mail item by controlling the item transverse moving mechanism and (c) registering the mail item during printing by controlling the item registration arrangement. (a) moving the carriage back-and-forth along the longitudinal direction; (b) indexing the mail item by controlling the item transverse moving mechanism and (c) registering the mail item during printing by controlling the item registration arrangement.