Refused (REF)
The USPS defines this NIXIE code as the addressee refused the mail outright or refused to pay any additional postage due. You can combat this by ensuring sufficient postage is affixed to the mail piece, but even that cannot prevent someone from accepting mail they do not want.
This is typically caused by not having sufficient postage affixed to your package and is most common when shipping larger items in envelopes, like a small gift or a book in an envelope that would typically require additional postage due to weight.
This NIXIE code has a very low returned rate, the FY25QTR1 report from the USPS shows less than 1%
| UAA Reason | UAA Reason Description | All Industries |
| COA | Change of Address | 20.73% |
| G | Box Closed - No Order | 0.11% |
| K | Moved left no Address | 1.56% |
| W | Temporary COA | 3.21% |
| A | Attempted, not Known | 15.76% |
| E | In Dispute | 0.06% |
| I | Insufficient Address | 8.25% |
| L | Illegible | 0.07% |
| M | No Mail Receptacle | 2.86% |
| N | No such Number | 2.90% |
| P | Deceased | 0.25% |
| Q | Not Deliverable as Addressed/Unable to Forward/Forwarding order expired | 32.59% |
| R | Refused | 0.67% |
| S | No such Street | 1.05% |
| U | Unclaimed | 2.45% |
| V | Vacant | 7.48% |
| Total | 100.00% |