The content of this book suggests that the second half of the fifth century B.C. was the time of Malachi's active ministry. The temple had already been recuilt. The religious conditions - apostasy, intermarriage with foreign women, neglect of the tithe - are similar to those prevaling during the era of Nehemiah (444-432 B.C.).
Malachi's chief concern is that the Israelites' relationship with God is not as it should be. They have neglected and mistreated God. They do not respect God as they should, failing to observe that which God requires of them. Consequently, judgment awaits them, but the God-fearing people are assured that they are noted in God's book and will enjoy God's salvation forever.
Outline:
I. God's love for Israel 1.1-5
II. Israel offends God 1.6-2.17
III. God's requirements 3.1-15
IV. The righteous and the wicked 3.16-4.6