Canon 8
That representative letters for presbyters excommunicating from the diocese can only be issued by bishops.
Even rural presbyters are not allowed to send canonical epistles, except when they send letters to neighboring bishops. But impeccable chorebishops can give peace certificates.
Greek original
Μηδὲ πρεσβυτέρους τοὺς ἐν ταῖς χώραις κανονικὰς ἐπιστολὰς διδόναι, ἢ πρὸς μόνους τοὺς γείτονας ἐπισκόπους ἐπιστολὰς ἐκπέμπειν· τοὺς δὲ ἀνεπιλήπτους χωρεπισκόπους διδόναι εἰρηνικάς.
Parallel canons
Ап.121333IVВс.1113Трул.17Анкир.13Антиох.10Лаод.4257Карф.32106