The ornamental design for a letteropener, as shown and described.
FIG. 1 is a perspective view of a letter opener showing our new design;
FIG. 2 is a front view thereof, the rear being identical;
FIG. 3 is a side view thereof, the opposing side being identical;
FIG. 4 is a top view thereof;
FIG. 5 is a bottom view thereof; and,
FIG. 6 is an enlarged cross-section view thereof taken along line 6-6 indicated in FIG. 2.
The broken lines shown in the drawings are included for purposes of illustrating portions of the letter opener that form no part of the claimed design.