Translation:The courier carries many letters.
In French, it's with 2 "r": courrier. Yes, from "courrir" = to run. The old meaning for "courrier" was the person who ran to carry a message.
And it became rather, courrier = mail, letter, in modern French.
I think instead of "courier", it could also be translated by "messenger".
Tabellarius, is derived from tabella, same root than the English tablet, via the French table, tablette. A "table" was everything that was flat, so also the tablets of stone, or clay, used before the invention of the wood paper of the animal paper (vellum).