As a box code, 1621 is used for 10 post office box locations.
PO Boxes using 1621
| Suburb | Town | Province |
|---|---|---|
| Birch Acres Ext 24 | Kempton Park | Gauteng |
| Birch Acres Ext 28 | Kempton Park | Gauteng |
| Birch Acres Ext 31 | Kempton Park | Gauteng |
| Birch Acres Ext 32 | Kempton Park | Gauteng |
| Birch Acres Ext 33 | Kempton Park | Gauteng |
| Birch Acres Ext 34 | Kempton Park | Gauteng |
| Birch Acres Ext 43 | Kempton Park | Gauteng |
| Birchleigh | Kempton Park | Gauteng |
| Jukskei View Ext 17 | Midrand | Gauteng |
| Jukskei View Ext 18 | Midrand | Gauteng |