Boxberger (back) will begin a rehab assignment with High-A Charlotte on Sunday, Marc Topkin of the Tampa Bay Times reports.
Boxberger is scheduled for roughly six rehab outings over the next three weeks as he recovers from a right flexor strain, so it will take some time before the right-hander is able to return to the Rays' bullpen. It's already been a strenuous journey back for the reliever, who has yet to pitch this season after posting a 4.81 ERA over 27 games in an injury-marred 2016 campaign.