•  Acceptable containers include corrugated or solid fiberboard, paperboard (for small    items), metal cans, tubes or boxes, wooden boxes, and fiber mailing tubes with    metal ends.  The strength of the tube ends must be equal to the tube side-wall    strength, unless the contents are lightweight, rolled items.

•  For easy loads of up to 5 pounds, paper bags and wraps are acceptable when at    least of a 50-pound basis weight (the strength of an average large grocery bag), and    the items are immune from impact or pressure damage.  Do not use string or    staples to secure packages.

•  Cellophane and masking tape may not be used for closure or reinforcement of    packages but may be used to augment adhesive closures on envelopes or to cover    staples on bags.  Except for pressure-sensitive filament tape, tapes used for    closure and reinforcement may not be less than 2 inches wide.  Non-reinforced    plastic tapes must be at least as strong in the cross direction as in the machine    (long) direction.

•  Packages containing breakable items should be marked “Fragile” above the    address, below the postage, and on the reverse side.  Those containing foods or    other items which would decay should be marked “Perishable.”

•  Address information should be clearly typed or printed on an address label placed    in the center of the parcel.  The “To:” and “From:” should be clearly indicated.

•  Indicate what class the package should be sent.  All packages with no mail class    indication will be sent First Class.