Malachi is a short prophetic book, the name Malachi just means “my messenger” which seems to be what the speaker calls himself. It has no more details of time, place or person in the superscription (as most prophetic books do), but the content suggests Judah after the exile under Persian rule.
The book opens opens with a strong statement of Yahweh’s election of Israel, using hyperbole (exaggeration) to make it’s impact. “Malachi” accuses his audience of being willing to obey and seek to please humans but not God! He calls for proper sacrifice cf. pre-exilic prophets who were less impressed by sacrifice. The book usually signals when others words are being imagined, making it easier to read.
It addresses priests much of the time and the greater importance of priests, sacrifice and law/torah is a feature that suggests the time when Israel was province.
Malachi’s mix of concern for the here and now and for the future is typical of prophetic books, but this book is more weighted to future than most. More than any other short prophetic book Malachi prepares for and links to the New Testament.