What is the meaning/message of "On This Long Storm The Rainbow Rose" by Emily Dickinson?

In the first stanza, the poet talks about the aftermath of a storm. There is a rainbow, and the sun is coming out. The clouds are parting, but they move like "listless elephants." The word "listless" means lethargic or sluggish. So, the clouds are parting very slowly. The setting is almost languorous. It is as if the clouds can't be bothered to move.
Meanwhile, the "horizons" are said to be "straggled down." The word "straggled" can mean one of two things. The first meaning refers to someone lagging behind a group, while the second meaning refers to an undefined, even irregular spread. The first stanza talks about the aftermath of a storm, when the air is still heavy with moisture. Fog in some places near the horizon may cause the horizon line to look undefined. The setting makes the general mood of the first stanza lethargic, even dreamy.
The second stanza begins on a positive note. The birds can finally emerge from their nests; the strong winds have subsided. However, the last two lines shock us: someone did not survive the storm. The eyes that used to gaze upon the beauties of summer are now "heedless." They can no longer see.
The third and last stanza talks about the "quiet nonchalance of death." The dead woman need no longer concern herself with the challenges of earthly life. So, she lies quietly composed. No "Daybreak" can "bestir" her, but the "Archangel's syllables" will soon awaken her. She will no longer live an earthly life but will be given an immortal existence after the Archangel (depending on your faith, Michael or Gabriel) resurrects her. The last stanza implies that death is a gift.