Php 1:1-2 1 Paul and Timothy, servants of Christ Jesus,To all the saints in Christ Jesus who are at Philippi, with the overseers and deacons: 2 Grace to you and peace from God our Father and the Lord Jesus Christ.
Paul in prison takes time to write to the Philippians and acknowledging his son in the faith in the epistles. This church at Philippi was dear to him, he had the deepest personal affection for them that there was no need of a formal introduction. He is not writing by first referring to the title of his call as an apostle as in other epistles but as a servant of the Lord and a servant to those he ministered to. He calls them saints including overseers and deacons, which is to say, saints are those who have repented and trusted in Christ alone for their salvation. The are no second class christians in the kingdom.
Having acknowledged the saints in Philippi, he offers warm salutation as a way to show that he wanted the best for them by first laying the foundation. He makes it clear that even the peace and unity we enjoy is from God. The introduction and tone is important.