We claim the ornamental design for an outlet box, as shown and described.
FIG. 1 is a front/right/top perspective view of the outlet box;
FIG. 2 is a back/left/bottom perspective view thereof;
FIG. 3 is a front elevational view thereof;
FIG. 4 is a rear elevational view thereof;
FIG. 5 is a left side elevational view thereof;
FIG. 6 is a right side elevational view thereof;
FIG. 7 is a top plan view thereof; and,
FIG. 8 is a bottom plan view thereof.
The dash-dot lines and broken lines immediately adjacent the shaded areas represent the bounds of the claimed design, while all other broken lines are directed to environment; the dash-dot lines and broken lines form no part of the claimed design.