Abstract This paper examines the phraseology of three epistolary formulae—namely, the formula valetudinis initialis (opening health wish formula), the formula of joy, and the καλῶς ποιήσεις formula, in Greco-Egyptian private letters written between the first century bce and third century ce. In particular, we observe that the letter writers make an opening health wish customarily when the letter recipients’ position/status is higher or at least equal to the writers—but rarely when the recipients’ position/status is lower than the writers. Furthermore, when the opening health wishes were made in expanded and reconfigured forms, they signal intensified courtesy to the recipients. The formula of joy also reinforced the favourable atmosphere when persuasion or request was intended. In this vein, the expanded and reconfigured formula valetudinis initialis used together with the formula of joy in 3 John 2–4 shows that the Elder does not intend to write his letter from the position of a higher authority. Furthermore, in requesting hospitality, he uses the καλῶς ποιήσεις formula, indicating his intention to persuade Gaius, whom he also includes in ‘us’ (3 John 12). Thus, the epistolary rhetoric of 3 John fits better with a correspondence between partners rather than an exhortation in an institutionalised hierarchy, unlike the case of the Ignatian letters.