Scans are only displayed when mail requests are processed by USPS as it makes its way through the mail stream. The Return To Sender (RTS) event scan occurs when the delivery of a mailpiece is attempted by USPS but the mail is re-routed after being deemed undeliverable or misdeliverable.
This results in a “Return to Sender” yellow sticker being affixed to the mailing by USPS, and for Lob’s tracking purposes, the mailpiece is treated as a “new” letter that is going to a new destination (the re-route location). This may be why the same mailpiece may receive new scans after receiving the RTS event.
A multi-delivery attempt is translated into scans in “Delivery Attempt 1 and 2” below, compared to a standard delivery where the mailpiece makes it to its final destination in a single attempt:
| Standard Delivery Process | Delivery Attempt 1 | Re-Routed Attempt 2 |
| Received | Received | - |
| In Production | In Production | - |
| Mailed | Mailed | - |
| In Transit | In Transit | - |
| Processed for Delivery | Return to Sender | In Transit [+Yellow Sticker] |
| (Delivered) | - | Processed for Delivery |
| - | (Delivered) |
*Note: USPS may not consistently scan all mailpieces at every stage
Example of a Return to Sender sticker:
Because RTS scans are not necessarily an “end-state scan”, you should not track whether it was the last scan received when trying to calculate the percentage of RTS mail, as it may have been marked as such and still received additional scan events. Instead you should try calculating the percentage based on whether the RTS scan event was ever received, regardless of its place in the sequence of scan events.