LTŠiuo metu profesoriaus Arnoldo Piročkino rupesčiu yra paskelbti 424 Jono Jablonskio laiškai (Jablonskis 1985; Jablonskis 1991). Dauguma šiyų laiškų rašyti lietuviškai (353), kai kurie rusiškai (70), o vienas lenkiškai. J. Jablonskio laiškų turinys paprastai dalykinis, todėl juose maža asmeniškumo ar emocijų. Šia prasme kiek labiau skiriasi laiškai sūnui Konstantinui, dalis Kazimierui Jokantui skirtų laiškų ir dar vienas kitas. Kreipinius J. Jablonskis laiškuose paprastai vartoja tik laiško pradžioje arba išvis nevartoja. Laiškai be kreipinių pagal parašymo tikslus esti dvejopi: 1) skirti aptarti rūpimos kalbos, knygų leidybos ar visuomeninių organizacijų veiklos klausimus (plg. Jablonskis 1985: 47, 94, 324-352 ir kt.); 2) adresuoti įvairių įstaigų vadovams. Pastarieji laiškai paprastai pradedami adresato įvardijimu, pvz., Prof M. Biržiškai, humanitarinio fakulteto dekanui; Švietimo Ministeriui K. Jokantui; Humanitarų Fakulteto Dekanui prof. V.Krėvei-Mickevičiui. Panašiai elgiamasi ir kai kuriuose laiškuose, skirtuose Juozui Tumui. Jie tai pat neretai pradedami adresato luomo įvardijimu (Kun. J. Tumui), o vėliau arba pavartojamas kreipinys, arba rašoma visai be kreipinio. Žinoma, vienas kitas kreipinio neturintis laiškas yra kotoks, nederantis į minėtas grupes. [Iš teksto, p. 256].
ENThe majority J. Jablonskis’ letters are written in Lithuanian (373), part of them are written in Russian (50) and only one - in Polish. In the Lithuanian letters the adress is usually some form of adjective. The form Gerbiamasis is used very often. Sometimes we come across brangusis and very seldom mylimasis. There are extended address forms consisting of adjectives and nouns: mano mylimasis, mano brangusis, mylimas drauge, brangus drauge. Only once J. Jablonskis uses the colloquial form Sveikas gyvas! The person whom he addresses is not known to us. The address consisting of a vocative noun is not typical of these letters. The form brolau apears rather only frequently and Varkeli is used to address his son Konstantinas. J. Jablonskis addresses V. Kudirka with very worm words: Vincuti Brolau. There are no more personal names in the letters written in Lithuanian. The addresses in the letters written in Russian are quite different. We come across number of epithets used together with names and patronymics: Vaše Vysokoprevoschoditelstvo Afanasij Fiodorovic, Milostivij Gosudar Gavril Afanasjevic, Vase Prevoschoditelstvo Aleksej Aleksandrovič, Mnogouvažajemij Aleksej Aleksandrovič. Professor E. Volter is addressed with the words Mnogouvaajemij Eduard Aleksandrovič in the Russian letters, and with the words Mano brangusis in the Lithuanian letters. The addresses in the letters written in Polish to the famous linguist J. Karlovich are very refined: Szanowny i łaskawy Panie! Dobrodzieju! It could be said that J. Jablonskis considered the etiquette of the letters written in the Lithuanian language more simple, closer to the colloquial speech which does not demand a higher style. That is why close people and those having many things in common with J. Jablonskis are usually addressed warmly-brolau, in other cases adjectives axpressing respect are used.The same person can be addressed in different ways depending on whether J. Jablonskis writes to him as to samebody higher in office or to a person sharing common ideas. His letters evidence that J. Jablonskis paid great attention to the position the person he was writing to occupied, as well as to their personal relationship, choosing the language accordingly.