It's a Newbie anti spam measure, it won't happen anymore once your account is more mature.
This one is new to me, I never knew the forum had such a feature in place, probably because I didn't post alot of links when I was a newbie, can't even remember posting links at all
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All I remember was that login in to the forum was hell when my account was pretty new, I had to always type in/pass a captcha verification, in other words, anti-bot verification before I could login to the forum, i don't know if that feature is still in place right now, it was one I hated with passion
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