Only mail sent within the U.S. and with a 5-digit zip code qualifies. Parcel post is printed matter, merchandise, or other mailable material that weighs more than 16 ounces. Special standard materials can weigh less than 16 ounces. Domestic express mail guarantees overnight delivery service of mailable material up to 70 pounds to most zip codes in the U.S. International service can be used to send documents and small packages to over 100 foreign countries. However, next day service guarantees are not possible internationally.
Express mail is insured against loss, damage, or rifling at no additional cost.
Packages that appear to have been insufficiently prepared will not be accepted for mailing. A return receipt may be requested to show written evidence of delivery. International postal insurance is available to some countries for parcel post only. Insurance limits vary from country to country. The USPS will not reimburse mailers in amounts higher than proven value.