The paper is a publication of three diplomatic letters signed by Shah Safi I: two of them addressed to Tsar Mikhail Fedorovich and one to his father, Patriarch Filaret. The inventory annotation of all three documents (Russian State Archive of Ancient Acts, fund 77 “Relations between Russia and Persia”, inv. 2) contained an erroneous dating. Comparison of each letter with the documents from the first part of the same collection (fund 77, inv. 1) has allowed the authors to correct their approximate dating and evaluate their significance in the context of the foreign policy and the goals pursued by the embassy delegations that delivered the letters. The publication of all three documents is accompanied with the documents' description and translation of their texts into English.