Riefenhauser was released by the Astros on Saturday, Jake Kaplan of the Houston Chronicle reports.
Riefenhauser, who had signed a minor league contract with the Astros, picked up a save in his final spring appearance for Houston on Friday. The 27-year-old left-hander, who has 24 games of MLB experience as a member of the Rays, had a 2.35 ERA over 7.2 spring innings. He allowed three runs on five hits and seven walks while striking out five.