This happened on World Building subwebsite. I'll try to post my answer below the separator line if the anti-spam will allow me.
Please, can I get any help on why is this considered a spam message, because I have no clue what that bot thinks I'm selling. What should I cut from this answer? I spend a lot of time writing this and it's really annoying that I'm not allowed to post. I have a hunch the bot detects "dwarven" as a misspelling of some unrelated word or simply doesn't like the repeation (which hardly can be avoided if I'm talking about dwarves and nothing else). Another theory of mine is that anti-spam bot doesn't like the s*x word, and considering that I was writing about evolution, mostly s****l selection, maybe it assumed I was promoting some sleazy website.
No luck, still getting flagged as spam. Here is the pastebin link: https://pastebin.com/dJk0JdQ8
And just for completness, the link to the question I was trying to answer: Why might dwarves be black skinned in a medieval fantasy world?
Edit: below is the error message after I press "Post Your Answer" as requested. It shows up every time I try to post, even after refreshing the page.
Update: I thought that maybe posting from behind the proxy and/or in private mode might have been an issue, so I tried to post from my home PC and the problem still persists. There must be a problem with contents of the answer itself. I've read a little more and it appears that spam-bot is very rudimentary, counting trigger words appearing frequently in spam campaigns and nothing else. It's not hard to imagine that race might be such trigger word, either used in political, racist context or trolling campaigns. Evolution can be flagged for creationists spam campaigns. Combination of sex, race and evolution in a very long post most likely raised more red flags that 1st May on the Red Square.
Update2: as advised, I posted a short test answer and it was accepted. After that I was able to edit the answer and paste the actual answer in it's place. However, the spam filter is unacceptable and circumventing it by exploiting what is basically a security gap is not really an answer. I leave this question up because I feel this still should be properly resolved.