Paul wrote the letter to the Philippians by Epaphroditus, after he had recovered his health.

Paul wrote the letter to the Philippians by Epaphroditus, after he had recovered his health. He hoped also that in a short time, he would send Timothy to them. As soon as he would know their state, he trusted also that he himself would come shortly to them. (PHP 2:2,19,29) At that time Paul's bonds for Christ were famous in all the court and even some of Caesar's palace staff were converted to the faith. (PHP 1:12,13 4:12) Since he was sent into prison by Caesar, he was more known in his family and so made the house of persecution the church of Christ. {Jerome, Commentary to Philemon}