FIG. 1 is a front view of a structural post as showing our new Design; FIG. 2 is a rear elevational view thereof; FIG. 3 is a right side elevational view thereof; FIG. 4 is a left side elevational view thereof; FIG. 5 is a top plan view thereof; FIG. 6 is a bottom view thereof; FIG. 7 is a cross sectional view taken along line 7—7 in FIG. 5. FIG. 8 is a perspective view thereof; and, FIG. 9 is another perspective view thereof.