The other attributed prophetic books include one or more of
- prophetic or priestly title
in the attribution. Some of the attributions also have an indication of date of the prophecy. Malachi is the only attributed OT text without any of these. The LXX apparently assumes that the text read "Malachiyah", a proper name that can also be a geonymic. The difference is a final letter "he", or "he" "vav" which were commonly not written but assumed in names in everyday writing. However, this might only indicate the bias of the LXX translator who wanted to interpret the name as a proper name.
We have no other identification of Malachi in the OT or externally. That is, no other references to him, no information about him and no other writing attributed to him. The Babylonian Amora, Rav Nachman ben Jacob (circa 250-320 CE) is quoted as saying that Malachi is in fact Mordechai of the book of Esther (tractate Megillah ["Scrolls"] page 15, side A in the Vilna Rom edition). This might sound far-fetched, but it does indicate that some established scholars accepted the opinion that "Malachi" is a pseudonym or adjectival.
There is no clear stylistic or theological similarity to other OT texts that would indicate a link to another prophetic figure.
The opening verse differs from most other books in that is uses the the word "b'yadei", meaning "by the hands of", so that a more literal translation would be "The content of the word of the LORD to Israel by the hands of my messenger". Hagai uses "by the hand of" (singular) but also includes a date and title "the prophet Hagai". Other opening lines use the verbs for God speaking to the prophet (e.g. Zachariah), or use "the word of the LORD to" (e.g. Zephaniah). In Malachi, the "to" is not "to the prophet", but "to Israel", as if to say that the prophecy in this case is directly to all of Israel through a messenger or angel. Perhaps the writer intended that this word of the LORD could be heard by everyone who was sensitive enough, even without the agency of a particular prophetic individual. This could be the precursor of the late second temple concept of a "bat kol", a heavenly voice not spoken by anyone in particular but heard by everyone. None of the classical interpreters make this interpretation though.
Our interpretation of the text might be changed if we were able to establish a likely link to another OT figure or text. As this is not the case, it makes little difference to our interpretation whether "malachi" is "malachi", "Malachi" or "Malchiyahu".
The book is very late, and might have been written at a time when there was already resistance to public claim of prophecy by living writers. At some point during the Second Temple, it was commonly accepted that the age of prophecy had closed, and this became Pharisaic doctrine following the victory over the Sadducees for control of the Temple during the reign of the Maccabees. Since the subject matter of Malachi does not lend itself to pseudepigraphy, the only acceptable attribution left is an anonymous attribution to a "messenger" who is not called a "prophet". This is just ambiguous enough to allow the text to be accepted as prophecy a short time later despite it being written after the presumed close of prophecy and not being believably attributable to a previously accepted prophet.