Mo. Rev. Stat. § 21.270
When the general assembly recesses for more than fifteen days and less than thirty days all bills and joint resolutions passed by both houses and presented to the governor for consideration shall be returned within fifteen days after presentation to the office of the secretary of the senate or chief clerk of the house, according to the origin of the bill or joint resolution, with his approval or reasons for disapproval. The office of the secretary of the senate and the office of the chief clerk of the house shall be kept open during the period of recess to receive any bills and joint resolutions from the governor. The secretary of the senate or chief clerk of the house shall present all bills and joint resolutions received from the governor to the house of origin when the house convenes in session after the recess.
§ 21.270, RSMo