The CM postcode area, also known as the Chelmsford postcode area,[2] is a group of 25 postcode districts in England, within 16 post towns.
These cover central Essex (including Chelmsford, Harlow, Brentwood, Billericay, Braintree, Burnham-on-Crouch, Dunmow, Epping, Ingatestone, Maldon, Ongar, Southminster, Stansted and Witham), plus a small part of east Hertfordshire (including Bishop's Stortford and Sawbridgeworth) and a very small part of the London Borough of Havering.
The southern part of the CM7 district for Braintree was recoded to CM77 in 2002.
[3] The Stansted post town (CM24) is entirely surrounded by the Bishop's Stortford post town (CM22 and CM23).
[2] The approximate coverage of the postcode districts: