In the early spread of Christianity Paul wrote several letters to churches in various places. How were the letters distributed, did they have a postal system anything like ours?
There's always more that can be said, but you might find my answer here interesting: https://www.reddit.com/r/AskHistorians/comments/bwc19i/what_would_writing_and_sending_a_letter_involve/epzfodn?utm_medium=android_app&utm_source=share