CO - Colchester
The postal area CO (Colchester) comprises of the following post towns; these towns should be written in capital letters when used in addresses.
Postal Districts within CO - Colchester
| Country | Post Town | Postal District |
| England | Colchester | CO1 CO2 CO3 CO4 CO5 CO6 CO7 |
| Bures | CO8 | |
| Halstead | CO9 | |
| Sudbury | CO10 | |
| Manningtree | CO11 | |
| Harwich | CO12 | |
| Frinton-on-Sea | CO13 | |
| Walton-on-the-Naze | CO14 | |
| Clacton-on-Sea | CO15 CO16 |
