How Long Is a Package Held for Mailability Determination?

A package held for a mailability determination is typically held for up to 21 days. That window comes from the Administrative Non-Mailability Protocol USPS uses when it suspects a parcel contains prohibited contents: the Postal Service pulls the package from the mailstream, tries to reach the sender or recipient, and waits for a response. If no one responds within 21 days, the package is declared abandoned and can be opened without a warrant.¹

What USPS Does During the Hold

Once a package is flagged, it moves to a postal facility for review. Postal employees or inspectors assess the outside of the parcel and try to determine what’s inside. During this period, USPS contacts the sender or recipient to request information about the contents or consent to open the package.¹

Tracking during this period usually shows a status along the lines of “held for mailability determination.” That message means the package is stationary at a facility while the review runs. It is not moving toward the destination, and it will not move again until USPS makes a decision or the 21 days run out.

What Happens After the 21 Days

The end of the hold produces one of three outcomes, depending on what’s in the package and whether anyone answered the notice.

If the contents are confirmed mailable, the package continues to the original recipient.¹
If the contents are confirmed nonmailable, USPS seizes and disposes of them. Federal law gives the Postal Service broad authority to dispose of nonmailable matter as it sees fit.²
If neither sender nor recipient responds within 21 days, the package is treated as abandoned and can be opened without a warrant, at which point the mailable-versus-nonmailable outcomes above apply.¹

Items that reach the delivery office can sometimes still be delivered if the recipient provides the sender’s name and address.² The 21-day figure is the ceiling on the administrative hold itself, not a guaranteed clock; a determination can come sooner if the contents are quickly identified or the sender responds promptly.

What to Do If Your Package Is on Hold

Respond to any USPS notice as soon as you receive it. Silence is what triggers the abandonment outcome, and it also stretches the hold out to its maximum length. If you can describe or document the contents in a way that resolves the question, the review can end early and the package can move again.

Provide information about what’s inside, how it was packaged, and, where relevant, any prior mailability guidance you relied on. If USPS asks for consent to open the package, understand that refusing consent does not extend your protection past 21 days: after that point, consent is no longer required.

Why Packages Get Flagged

Hazardous materials drive most mailability reviews, and USPS puts the burden on the customer to determine whether an item qualifies as hazardous before dropping it off.³⁴⁵

A domestic mailability history does not carry over to international mail. International shipments face country-specific restrictions that can prohibit items USPS accepts domestically, so a package with the same contents that moved fine last month within the U.S. can still be flagged when routed abroad.⁵

Even a valid prior ruling from the USPS Pricing and Classification Service Center does not guarantee your package will move. Rulings remain valid only as long as the item, its packaging, and the governing regulations are unchanged, and USPS retains authority to refuse any package it considers nonmailable or improperly packaged.⁶ Regulations shift as well. USPS adopted new requirements in 2025 mandating rigid outer packaging for all hazardous material shipments and changing quantity limits for certain toxic materials like pesticides and herbicides.⁷

What Happens If the Contents Are Prohibited

Beyond seizure of the package itself, mailing prohibited items can carry civil and criminal penalties.

Civil fines apply to anyone who knowingly mails nonmailable hazardous materials. The base statute sets a minimum of $250 per violation plus cleanup costs and damages.⁸ Those figures are adjusted for inflation, and as of the most recent published adjustment the range runs from $393 to $156,422 per violation.⁹ “Knowingly” here does not require an intent to break the law; it is enough that a reasonable person exercising reasonable care would have known the item was nonmailable.

Criminal penalties are more serious. Knowingly mailing any item declared nonmailable can result in a fine and up to one year in prison. If the mailing was done with intent to kill or injure someone, or to damage the mail or other property, the maximum rises to 20 years. If someone dies as a result, the sentence can be life in prison or the death penalty.¹⁰

If you disagree with a nonmailability finding once the review is complete, USPS provides a three-level appeal process starting with the Pricing and Classification Service Center and ending, if needed, with the Postal Service’s Judicial Officer.¹¹

1
USPS Office of Inspector General. U.S. Postal Inspection Service Handling of Suspected Marijuana Packages
2
Office of the Law Revision Counsel. 39 USC 3001 – Nonmailable Matter
3
USPS. Domestic Shipping Prohibitions, Restrictions, and HAZMAT
4
Postal Explorer. USPS Packaging Instruction 9D – Lithium Metal and Lithium-ion Cells and Batteries – Domestic
5
Postal Explorer. Mailable Dangerous Goods
6
Postal Explorer. Publication 52 – Hazardous, Restricted, and Perishable Mail – Section 215 Requests for Rulings
7
Federal Register. New Mailing Standards for Hazardous Materials Outer Packaging and Nonregulated Toxic Materials
8
Office of the Law Revision Counsel. 39 USC 3018 – Hazardous Material
9
eCFR. 39 CFR 233.12 – Civil Penalties
10
Office of the Law Revision Counsel. 18 USC 1716 – Injurious Articles as Nonmailable
11
Postal Explorer. Publication 52 – Hazardous, Restricted, and Perishable Mail – Section 214 Appeals