Thank you, Sylvia.
Colossians 4:16? In the NRSV it reads:
"And when this letter has been read among you, have it read also in the church of the Laodiceans; and see that you read also the letter from Laodicea."
We should not imagine a "church" in terms of today's understanding. There would be a handful of people, possibly meeting in a shop or someone's house. As the sentence indicates, few could read and even fewer could write. Thus the writer of this letter (epistle) expected it to be read out to them and then to the group at Laodicea. I cannot confirm what the letter to the Laodiceans said.
So I see these as circulars, designed to keep the groups advised (and managed).
Paul, Jesus, and the Baptist were convinced that the "end" was imminent, taking place in their own day. We can hear the questions in the minds of the Thessalonians as they grappled with the fact that it had not yet taken place, and some of them had even died before the cataclysmic divine intervention had taken place. With his determination that the end was upon them, Paul was never concerned about church organisation or structure -- or being married. But by the end of the first century, wild enthusiasm gave way to sombre reflection that time had passed without anything happening.
So we read instructions regarding church structures, organisation, and the need to be married creeping in. This is just one of the reasons that scholars do not believe Paul had any hand in the Pastorals (Timothy, Titus). There are, of course, other indicators.
May I throw another one at you, if you do not mind? The book of Acts is widely accepted as being the product of the early second century and that it is a carefully crafted religious novel. And do not think that the Gospels present an actual biography. The earliest (Mark) was written 40 years after Jesus was executed. Matthew was written by another group about 15 years later - long after Jeruslem had been attacked by the Romans. These people had no written record of what Jesus said or did. Jesus did not write anything nor did any of his immediate hearers. They lived in an oral society, relying on memory.