Allowing Guest User Posting

Fastpath: Admin Console: Ideas > Idea Settings > General

You can allow community users to post ideas anonymously as a guest. Posting as a guest can be useful when people in the community might be influenced in their voting by knowing who is posting. With this enabled, new ideas will display a check box through which someone can post anonymously. You can also hide the voting history so that users don't know who voted or how they voted.

To allow guest user posts, go to the Idea Settings page in the admin console and select Allow registered users to post as guest users.