To churches and individuals across the Mediterranean area. To Christian churches in Rome, Corinth, Galatia, Ephesus, Phillipi, Collossi, Thessaloniki amongst other churches but the letters to these churches are now lost eg the letter to the Laodiceans To individuals: Timothy, Titus and Philemon but there may be others that are now lost. The Letter to the Hebrews, traditionally placed in the New Testament after Paul's letters was probably not written by him.
the church
prison letters, or the letters of Saint Paul
Letters or epistles.
christians
Saint Paul
Saint Paul is the best known.
Paul sent letters (epistles) to various Churches in the areas he served.
I do not think so , as it was not clearly mentioned.
The new testament
The consensus of scholars is that Romans, 1 Corinthians, 2 Corinthians, Philemon, Galatians, Philippians and 1 Thessalonians are genuine letters written by the apostle Paul. Ephesians, Colossians, 2 Thessalonians, 1 Timothy, 2 Timothyand Titus were written in Paul's name, but long after his death.
There is no general agreement as to the exact years that Paul wrote his letters but, based on the chronology of Acts of the Apostles, the genuine epistles are usually dated to between 48 and 62 CE. Another view, based on the references to the collection that Paul spent so much effort and personal capital on achieving, is that the genuine letters were written between about 44 and 48 CE.
There is no Saint Paul chapter 20-21 in the Bible. The apostle Paul wrote several letters in the New Testament but none of them have 20 chapters