We've had a few spambots get in lately, so I've re-enabled a CAPTCHA.
This will appear:
1. When registering an account
2. When making a post, if the user's post count is 0
3. When sending a PM, if the user's post count is 0
I've set it to what SMF calls "medium" difficulty; which still looks perfectly readable to me. Hopefully it's not so readable to spambots.
If you're one of those users who sends PMs from time to time, but doesn't post on the boards; then (assuming you're not a spambot :P ), I'd suggest just finding an excuse to make one post somewhere or something like that, so you don't have to complete the CAPTCHA + security question each time you send a PM. Please note that the Forum Games board doesn't count towards your total post count, and as a side effect of this, posting there won't remove the security checks from your account.