Smith (elbow) threw off a mound Tuesday, Evan Drellich of CSN New England reports.
The right-hander suffered a setback in his rehab process in late April, but it appears that a bit of time off has gotten him back on track. He'll likely continue to work off a mound before facing live hitters in the next few weeks. Smith was transferred to the 60-day DL around the same time of the setback, so he likely won't be able to return to Boston's bullpen until the beginning of the summer.