A.J. Festugière (1898-1982), Epicurus and His Gods
, tr. C.W. Chilton (Cambridge: Harvard University Press, 1956), pp. 42-43, n. 3:
It is impossible not to compare the interest which Epicurus felt in his communities in Asia with the care taken by the apostle Paul of his 'churches'. On both sides similar occasions gave rise to an interchange of letters. Points of doctrine had to be settled—hence the great fundamental letters to Herodotus and Menoeceus (the letter to Pythocles would seem to have been put together from the π. φύσεως: only the beginning is genuine, cf. Usener, pp. xxxvii-ix). Or perhaps the communities are in trouble; the apostate Timocrates who has insinuated himself into the circle at Lampsacus is spreading scandalous libels against the master and his disciples (cf. Jensen, op. cit.). Or again, there are short letters of guidance and friendship.
References are to Hermann Usener, Epicurea
(Leipzig: B.G. Teubner, 1887), and Christian Jensen, Ein neuer Brief Epikurs
(Berlin: Weidmannsche Buchhandlung, 1933 = Abhandlungen der Gesellschaft der Wissenschaften zu Gottingen, Philologisch-Historische Klasse
, 3/5, pp. 1-94).