A beverage preparation machine (1) has: an extraction unit with a closed configuration for extracting a capsule (2) therein and an open configuration for removing the used capsule (2) therefrom; and a service unit (10) located under the extraction unit (20) and forming a receptacle having a collection cavity (11) for collecting the used capsule (2) and residual liquid projections (3) from the extraction unit (20). The service unit (10) has an upright wall (130) delimiting at least one through-passage (131) for favouring air circulation from inside the cavity (11) to outside the machine (1). The through-passage (131) is angled away from the direction of the liquid projections from the extraction unit (20) so as to inhibit the passage of the liquid projections through the through-passages.