| Clue | Source | Date |
|---|---|---|
| Narrow hole in a door | Wall Street Journal | 27 Nov 2023 |
| Letter opening | New York Times | 01 Mar 2023 |
| Opening in a door for letters | Newsday | 22 Aug 2022 |
| *Letter box access | LA Times Daily | 25 Nov 2019 |
| *Letter box access | The Washington Post | 25 Nov 2019 |
| Opening for a daily delivery | The Washington Post | 05 Aug 2016 |
| Letter drop | Newsday | 12 Apr 2015 |
| Door opening, of a sort | Wall Street Journal | 02 Mar 2015 |
| Letter drop | ||
| Opening for letters | ||
| Place to drop a letter | ||
| Letter drop |