We get a lot of questions concerning Undeliverable-as-addressed (UAA) mail. The USPS has a technical definitions as well as statistics on the return codes here: https://postalpro.usps.com/address-quality-solutions/undeliverable-addressed-uaa-mail , but often it's a combination of factors in your mailing.
- The individual, family, or business to which it is addressed has moved - are you using the correct address? When were your addresses last updated or when did you last validate that the recipient received mail at that address?
- The address is incomplete, incorrect, or illegible - are you using the correct codes?
- The addressee is unknown or deceased - are you scrubbing deceased records?
- The addressee refuses or fails to claim the mail - do you have permission or have you updated your do-not-contact lists?
- The necessary postage has not been paid - who prepared the postage for the mailing?
Here are most recent statistics on UAA Mail across all industries:
| UAA Reason | UAA Reason Description | All Industries |
| COA | Change of Address | 22% |
| G | Box Closed - No Order | 0% |
| K | Moved left no Address | 2% |
| W | Temporary COA | 4% |
| A | Attempted, not Known | 15% |
| E | In Dispute | 0% |
| I | Insufficient Address | 9% |
| L | Illegible | 0% |
| M | No Mail Receptacle | 3% |
| N | No such Number | 3% |
| P | Deceased | 0% |
| Q | Not Deliverable as Addressed/Unable to Forward/Forwarding order expired | 32% |
| R | Refused | 1% |
| S | No such Street | 1% |
| U | Unclaimed | 2% |
| V | Vacant | 6% |
| Total | 100% |
TrueNCOA can help you with most of these codes, but there's always going to be some returned mail.