In a context where the demand and supply of mail and parcel delivery services are undergoing major changes due to the widespread use of the Internet and digital communications, this paper focuses on the accessibility of postal services through the physical retail network. The accessibility constraints applied to the outlets network of Le Groupe La Poste (the French postal operator responsible for the universal postal service and three other services of general economic interest) are based on a “simplified” approach that considers accessibility only in terms of time or distance‐time. This paper proposes to measure potential spatial accessibility by applying postal supply and potential demand dimensions using a two‐step floating catchment area (2SFCA) analysis. Based on an equilibrium between supply and demand through distance function, this method, which is often used in studies of the accessibility of health services, is transposed and adapted into the field of postal activities. It aims to measure accessibility by taking into account the population and population/provider ratio, considering standard postal services provided at service points. While until recently the 2SFCA methods were mostly applied in healthcare contexts, some applications have been developed in non‐health‐related services over the last decade. This paper proposes an original contribution to analysing variations in the accessibility of postal services. Referring to the “primary postal services” (sales of stamps, letters or parcels postage, remittance of postal items, and so on), it outlines the conditions that activities (or services) must satisfy in order to use the floating catchment area method.