There is provided a cartridge assembly (4) for use in an aerosol-generating system, the cartridge assembly (4) comprising a cartridge (2) and a mouthpiece (26). The cartridge (2) comprises a cartridge body (6) and a cartridge cover (8), the cartridge body (6) having a first side defining a first recess (10) and a second side defining a second recess (12). The cartridge cover (8) comprises a cartridge cover cavity in which the cartridge body (6) is slidably received and an actuation aperture (24) for receiving an actuation portion of an aerosol-generating device. The cartridge assembly (4) is configured so that, when an actuation portion of an aerosol-generating device is received against the cartridge body (6) through the actuation aperture (24), the cartridge body (6) is slidable within the cartridge cover cavity from a first position to a second position. In the first position, airflow through the first and second recesses (10, 12) is prevented. In the second position, airflow through the first and second recesses (10, 12) is enabled.
