Question

Posting a message to a discussion forum that is completely off topic or appears to be promoting something may be considered _________ by the user community.

Answer 1

spam

Step-by-step explanation:

Answer 2

I believe the answer is: Spam

Spam is every efforts that users made in order to force some content or messages to the people who do not want to receive it.
In general, spam is used for either advertising purpose or for purposefully push a certain narrative/information on the site board.