Obsolete markings (from previous mailings or on reused boxes or containers)
must be entirely removed or completely obliterated prior to mailing.
Containers with improperly identified contents are not acceptable, as noted in
the following examples:
• A parcel marked "Bleach" that actually contains clothing is not
• A parcel marked "ART SUPPLIES" that actually contains a flammable
liquid is not acceptable, even if the liquid is technically an art supply like
paint thinner. The potential danger of the liquid's flammability must be
identified through the proper external markings required by 49 CFR and
Extraneous information (such as order numbers) that can be confused with
ZIP Codes may not be printed immediately under the last line of the address.
If other markings are used, such as advertising messages and company
logos, they must be placed in areas that do not conflict with the essential
information areas described in 5-1.