Blank and paperboard envelope formed therefrom

A blank for forming a paperboard envelope, the blank comprising:

• a single rectangular sheet of paperboard, having opposed top and bottom edges and opposed left and right edges,
• the sheet having a midline spaced equally from the left and right edges, the midline comprising a cut that extends from the top edge to a point spaced from the top edge and a fold line that extends from the point to the bottom edge, and
• the sheet having a first zone that extends from the midline to the right edge along the bottom edge, a second zone that extends from the bottom edge to a line spaced from the top edge, the line parallel to the top and bottom edges and disposed through the point, along the ridge edge, a third zone that extends from the midline to the left edge along the bottom edge, and a fourth zone that extends from the bottom edge to the line along the left edge,
• the first and second zones being configured to join the third and fourth zones, respectively, with the blank folded about the fold line,
• wherein the top edges form a closable opening with the first and second zones joined to the third and fourth zones, respectively, with the blank folded about the fold line,
• wherein a width from the fold line to the left or right edge is less than a length from the top edge to the bottom edge.