Within a mailing list post, *might* *might* be used when an outcome of something happening *might* be unknown. Furthermore, *might* *might* be used to indicate the probability of a negative outcome *might* be as likely as the probability of a positive outcome.
Somehow or other, usage of the term *might* over the term might, *might* balance out the perception in the reader of both positive and negative outcomes happening.
Unfortunately, usage of the term *might* *might* also create in the reader, a small perception of the author using the term *might* as slightly pretentious.
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Comment: A term that *might* be frequently found on mailing lists