The door “hung” down from the roof of the tent.  The letter also can mean the back and forth - or in and out movement -the door makes.  The word door in Hebrew begins with the letter Dalet דֶּלֶת.

יהודה

The name for the tribe of Judah contains all four letters of the Sacred Name except for the letter Dalet.  This suggests that the “doorway” to the LORD would come through the Tribe of Judah.

“So Jesus again said to them, ‘Truly, truly, I say to you, I am the door of the sheep. I am the door. If anyone enters by me, he will be saved and will go in and out and find pasture.’” John 10:7,9 (ESV)

“Behold, I stand at the door and knock. If anyone hears my voice and opens the door, I will come into him and eat with him, and he with me.” Revelation 3:20 Dalet is associated with the word “dal” #1800  דַּל  poor, low, needy.

The Father (Aleph) sent His Son (Bet) Jesus  by means of the Holy Spirit (Gimel) , who makes an appeal to the poor and needy (Dalet).

The Moshiach (Messiah) “Come to me, all who labor and are heavy laden, and I will give you rest.” Matt. 11:28