When the anti-spam code transitioned to a white-list, the benefit to being coy about the details lost out to the benefits of being much clearer, IMHO. If you get "permission denied" due to using a non-white-listed link, then we should probably just tell you that.

I'm still somewhat reluctant about just spilling the beans about the easiest way around that problem (include the URL but not as a link). My reluctance is due to there being a lot of evidence of spammers being willing to post tons of stuff that doesn't actually work as spam (it doesn't get posted or doesn't get seen by a search engine or lacks any links that the search engine would honor to increase the spam site's "page rank"). But the relative speed with which our most recent persistent spammer gave up after the lack of effect became clear gave me some hope that spammers sometimes can tell when spamming is wasting their own time, not just everybody else's.

So, just being clear on that second point as well is probably the right choice.

But, even better, I think, would be to let people try to link to whatever and just prevent non-white-listed links authored by low-level members from being seen by search engines (and requiring non-search-engine visitors to POST a confirmation before they can follow one).

So contributions on either of those fronts will be welcomed by me.

As to getting "permission denied" due to DB server load, I think that problem will just go away when I finish adjusting a few indices. I've done some of that work but it isn't totally non-disruptive to the site so I haven't finished those changes yet.

(Update: Actually, trying to post a non-white-listed link perhaps should require going through a confirmation page that informs you that your link will not be seen by search engines and will be a bit of a pain for others to follow.)