The goal of this article is primarily to highlight the phenomenon of the communication trough letter-writing from the city to its territory, from territory to territory or towards the inland regions, as a most important form of mobility in the corpus of Greek private letters. Entrusted to close relations or simply to passing people, who in turn confide it to other acquaintances, the letter travels a distance that its senders or its receivers have no doubt never entirely crossed: it is, somehow, the most seasoned traveller. In this way, it is the letter that puts in touch masters and subordinates, families, business partners and friends, whilst having the merit of giving an account of connected, renewed or abruptly-broken contacts. In the colonial environment, which is the result of a long-lasting coexistence, the shared practices operate between Greeks and the local populations, between Greeks of different origins established in the apoikiai, or with other Greeks. From these contacts, economic connections are established, which create a map of the territory and social networks. If some letters reported by the Demosthenic corpus underline the role played by letters in long-distance trade, ostraca and lead letters operate within a more restricted area. My paper focuses on the area where the messages are spread, emphasizing the local and regional networks, as attested by extant evidence.