Regardless of any advice pages, perhaps mandatory before 1st question by new user, how about getting the attention of everyyone who views any math overflow page?

Include a prominent banner on the top of every page, perhaps (with portions) in bold red.

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**For research-level math questions only.** See [link] for where to post non-research level questions.

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That sets expectations from the get go. Minimizes wastage of time for everyone.