>>535
You know, I was interested to ask this because this is the only image board I can name that messes with URLs. Somewhat reminded me of lame forums that you needed to register to follow links.
>Search engines can easily consider \`https://terrorism.org/\` a URL slug and tank Mathchan's rankings
Now that I think about it, I don't remember making a search on google and have an imageboard be one of the results, even when there's a thread that fits that search query better than any of the results that actually come up. Imageboards do come up if I search the name, so they're not all blacklisted. It seems (mainstream) search engines don't regard imageboards highly.
Is this actually because chans have an unusual frequency of naughty links? If that's true then cloaking is a good move for Mathchan. Or is that chans simply don't practice aggressive SEO to earn a place in the first page of results? 

I appreciate that resolving \`exit?u=\` doesn't rely on a database, and the encoded URL is just that, it can be decoded. But is a nebulous (AFAIK) search engine optimization principle worth the inconvenience? I think you downplay how inconvenient it is:
>If Mathchan is recursively mirrored then exit points ought to be mirrored with it too. Exit points contain a real URL so there would be no issue following the links on Mathchan's future archive.
I highly doubt there will be an anywhere near competent Mathchan archive. Only 4chan has dedicated archives, other chans at most have individual pages saved on the wayback machine. Links in Mathchan are broken in the Wayback Machine, and they're also broken when casually downloading one thread with \`Ctrl+S\`.

You underestimate your users' incompetence, and underestimate their competence at the same time. You expect users to be able to do recursive mirroring or base64 decode URLs. But you don't expect them to think before choosing to click link so you greet them with an obnoxious "Are sure you want to exit?" page. Nor do you expect privacy-conscious users to configure their \textit{own} browser to not send referer headers, if that's their concern. 
>1. To protect users from accidentally clicking on harmful links that are posted on Mathchan
>Links to some well-known sites (like Google, Youtube, Reddit, Twitter etc.) are distrusted by default because privacy conscientious users may not agree with privacy policy of these sites and do not want to let them know Mathchan was the site that referred them.