As you all know the whole world became a bit less “polite” or maybe it is better to say less formal. No one [“except me of course” still writes : [yours] sincerely… ] and all the greetings [for sure on the Internet ] became: Hi…..instead of Dear Sir or the like. Now I want to tell you that Hi now got a beautiful new status for me at least since I saw this Shabbath in the Torah Tidbits of the OU a very nice remark which I will copy here: hi (interjection) exclamation of greeting, originally to attract attention (15century) That’s what they say. We can claim it as RASHEI TEIVOT, initials of the greeting Hashem Imachem, May G-d be with you, first said by Boaz to his workers.So: You can greet all your friends now [even your Rabbi….??] with Hi [but do explain,please..!!]
4 Presently Boaz arrived from Beit Lechem. He greeted the reapers, “Hashem be with you!” And they responded, “Hashem bless you!”ד וְהִנֵּה־בֹעַז בָּא מִבֵּית לֶחֶם וַיֹּאמֶר לַקּוֹצְרִים יְהֹוָה עִמָּכֶם וַיֹּאמְרוּ לוֹ יְבָרֶכְךָ יְהֹוָה׃ In the Dutch Portuguese-Sephardic tradition in Holland all say יְהֹוָה עִמָּכֶם before Birkat ha-Tora as Boaz said But no one [as far as I saw/heard says this but instead: Ha-Shem imachem
My Ashkenazi teacher-Rav Michel Nager z”l- told me that it is better to say yיְהֹוָה עִמָּכֶם than Ha-Shem imachem in this case. as the purpose of the expression of Boaz was to really “renew” the use of G-ds name in a proper way.