Interest in the relationship between Paul's letter openings and Koine Greek letter-writing conventions has been steady for over a century, but little new data has emerged in recent years. In this study, Gillian Asquith offers a fresh perspective on Paul's epistolary practice by adopting a multidisciplinary method that synthesises sociolinguistics and lexicography. Comparing the language of Paul's letter openings with the register of language in documentary papyri, she demonstrates that high-register language in Koine Greek epistolary formulae contributes to warm and friendly relations between correspondents. Asquith argues that Paul creatively modifies epistolary norms by using unexpected, high-register language in the remembrance motif and litotic disclosure formula. Such usage, she posits, emphatically reassures Paul's recipients of his pastoral concern for them and heightens the persuasive force of his letters. Asquith's nuanced analysis contributes valuable new data to long-running debates around Paul's practice of prayer and the structure of his letters.