Different customs exist regarding the phrase "Le'alam U'l'almeh Almaya" in the "Yeheh Shemeh Rabba" response to Kaddish. Some recite this phrase this way, whereas others omit the letter Vav from "U'l'almeh" and recite simply "Le'almeh."
The Ben Ish Hai (Rav Yosef Haim of Baghdad, 1833-1909), in his work Od Yosef Hai, writes that the word should be pronounced "Le'almeh," without the letter Vav at the beginning. He explains that the "Yeheh Shemeh Rabba" response is meant to consist of 28 letters, and if the Vav is included, this response consists of 29 letters. Therefore, the Vav must be omitted. This is the position also of the Kaf Ha'haim (Rav Yaakob Haim Sofer, Baghdad-Jerusalem, 1870-1939).
This argument assumes that the word "Shemeh" in "Yeheh Shemeh Rabba" is spelled with a Yod (Shin, Mem, Yod, Heh). In some Siddurim, this word is spelled without the letter Yod, thus allowing for the Vav to be included in "U'l'almeh" without exceeding 28 letters. It is true that, as discussed in a previous installment, the Mahzor Vitri understood the phrase "Yeheh Shemeh Rabba" as a prayer that the divine Name, which currently contains only the letters Yod and Heh, should become complete, and according to this reading, the word "Shemeh" is read as "Shem Yod-Heh" ("the Name of Yod-Heh"). However, as we saw, Halacha does not follow this opinion, and therefore it is acceptable to omit the letter Yod from the word "Shemeh."
Moreover, Hacham Ovadia Yosef noted that Maran (author of the Shulhan Aruch), in Bet Yosef, clearly follows the opinion that the correct text is "U'l'almeh," and this is how the word appears in the texts of earlier Rabbis such as Rav Saadia Gaon, Rav Amram Gaon, the Rambam, and others. Hacham Ovadia asserts that in light of these sources, a Kabbalistic teaching involving the significance of the number 28 does not justify altering the text.
By contrast, Rav Meir Mazuz (1945-2025), who was a renowned expert in grammar, maintained that the correct text is "Le'almeh."
Rav Moshe Rahamim Shayo (contemporary), in his Mehkereh Aretz, writes that in the Bet Obed edition of the Siddur, which was used by the Jewish communities of Aleppo, Syria, the text reads "Le'almeh," without the letter Vav. This text also appears in the Siddur published by Rav Abraham Hamway, and this was the ruling of Rav Yeshayahu Dayan (1833-1903), head of Aleppo's Rabbinical court. There is also testimony that later, in the times of Aleppo's Chief Rabbi Moshe Mizrahi (1863-1955), Rav Mizrahi sharply reprimanded a member of the community who recited "U'l'almeh" instead of the "Le'almeh," which was the accepted custom in Aleppo. In the Kol Yaakob edition of the Siddur, which is used by many Syrian Jews, the word appears as "U'l'almeh," but this is a mistake, as the custom in Aleppo was clearly to say "Le'almeh."
In practice, therefore, it is proper for members of the Syrian community to recite "Le'almeh," and not "U'l'almeh."
Summary: In the "Yeheh Shemeh Rabba" response to Kaddish, the word "Le'almeh" appears this way in some editions of the Siddur, and in others, "U'l'almeh," with the letter Vav at the beginning. The text that should be followed by members of the Syrian community is "Le'almeh."