The USPS considers a mailpiece “nonmailable” if it cannot be accepted for processing even in non-automation areas, such as mailpieces not meeting minimum sizes or overweight mailpieces.
Items may be considered nonmailable based on different conditions, including:
- Violating minimum / maximum size or weight, or shape restrictions.
- Illegible address.
- Prohibited material.
If presented for mailing at a local Post Office™, nonmailable items are refused and not placed into the mail system.
What Happens if a Nonmailable Item is Mailed Anyways?
Sometimes a nonmailable item may be mailed anyway (such as dropped in a Collection Box® receptacle). Generally, nonmailable pieces are returned to the sender immediately as soon as the reason for nonmailability is discovered.
There may be rare cases where a nonmailable item is not directly returned to the sender, based on:
- Hazard of sending through the mail.
- Nonmailability is due to a legal violation.
- Packaging does not allow return or provide sufficient address to return.