Zoharic literature identifies mezuzah with the Sefirah of Malkhuth 1. Specifically, the doorpost (lit. mezuzah) is identified with Malkhuth, the feminine aspect of G‑dliness, while the mezuzah-parchment attached to the doorpost is identified with Z”A 2 (Zeir Anpin 3), the masculine aspect of G‑dliness, or with its lowest Sefirah, Yesod.

Thus, Rayah Mehemnah states that the Shekhinah (which is Malkhuth) is called mezuzah. It states further that the Tetragrammaton, inside the mezuzah, represents Ze’er Anpin, and the name Shad‑dai, on the outside, represent the Sefirah of Yesod or Kudsha Brikh Hu (the Holy One). In another place, Rayah Mehemnah states that mezuzah, on which the name Shad‑dai is written, is the Tzaddik, Righteous One, represented by the Sefirah of Yesod; the Shekhinah is the gate to which the mezuzah is affixed, as it is written:

This is the Gate of G‑d (Psalms CXVIII, 20).

Rabbi Chayim Vital states in the “Gates of the Commandments” that the doorpost represents Malkhuth. The mezuzah is placed at the bottom of the upper third of the doorpost. The upper third represents the chest of Z”A (Zeir Anpin), while the bottom of the upper third corresponds to Malkhuth (or Nukva 4 d’Z”A).

Similarly, in the “Gate of Introductions” he states that the place where the mezuzah is affixed is Nukva d’Z”A. The gematria of mezuzah is the same as that of Ado-nai (65), which hints to Nukva5. Nukva comes from behind Z”A. The purpose of the mezuzah is that the forces of evil, Klipoth (shells, husks) should not have a hold on the domain “behind” Z”A.

Z”A represents the male aspect of the Divine Persona while Nukva or Malkhuth represents the female. The Zohar explains:

And why is the female called Nekevah 6? Because she has more orifices than the male.

The place where mezuzah is affixed is called the chest of Z”A represented by the Sefirah of Tifereth. Tifereth is beauty and harmony, in this case the harmony between male and female in Divinity.