Boxberger was released by the Brewers on Friday, Adam McCalvy of MLB.com reports.
The 32-year-old was unable to secure a spot on the big-league roster to open the season, though Milwaukee apparently hopes to re-sign him to a minor-league deal. Boxberger had a 3.00 ERA, 1.39 WHIP and 18:8 K:BB over 18 innings for the Marlins last season.