The default spam control settings available in Soapbox will likely meet the needs of your site.  The likeliest setting you may wish to change will be to adjust the audience of which completion of the CAPTCHA tool.

To control this and other spam settings for Comments:

1. Go to Components > Comments
2. Click Options in the upper right
3. In the popup window under System Spam Options on the Spam tab, for Enable CAPTCHA, select No, Only Guests, or Anyone, the graphical word recognition tool to verify that the submitter is human and not a machine spamming the site
4. For Minimum Length, set the minimum number of characters that a comment can have to allow posting.  Default is 6.
5. For Maximum Length, set the maximum number of characters that a comment can have to allow posting.  Default is 1024.
6. User Flood Limit and Guest Flood Limit sets the number of seconds after which a user can post an additional comment.  The defaults are 30 and 1, respectively.  You should not need to change these settings.
7. For Enable reCAPTCHA, keep the default select of Yes.  reCAPTCHA is an enhanced version of CAPTCHA that allows for greater functionality, including the option for the end user to click a button to play an audio version of the words required by the tool.
8. reCAPTCHA Public Key and reCAPTCHA Private Key are unique to your site.  You should not need to change these settings.
9. Enable Moovur and Enable Akismet are set to No and do not need to be changed
10. Click Save