There are differences between the opening of Philemon and Paul’s other letters. As was customary, Paul provides his own name as the sender (on Paulos, see Col 1:1), but in his other, more formal letters he describes himself authoritatively as Paul an apostle. The absence of his usual title here perhaps signals the informality or intimacy that he is using, since he is writing to an old acquaintance. Paul is not writing to Philemon leveraging his apostolic influence, at least not overtly; he is sharing with him a concern, about which Paul is offering a solution.