Syndergaard (elbow) threw a bullpen session Tuesday, Tim Britton of The Athletic reports.
It marked the right hander's first time throwing off a mound since he suffered a setback in his recovery from Tommy John surgery in late May. While resuming mound work is a huge step for Syndergaard, he still figures to be multiple weeks away from beginning a rehab assignment, which means he's unlikely to rejoin the major-league roster until early September. Given those time constraints, the Mets have already alluded to the possibility of the 28-year-old serving in a relief role when he returns.