Thanks for getting back to me. I don't know how to remove the Cache from wpForo. I will see if I can get some help.
1. Check that user usergroup, edit that usergroup and make sure the "Can pass moderation" permission is checked/enabled
2. Make sure this user doesn't have unapproved topics and posts, find all unapproved topics and posts in Dashboard > Forums > Moderation admin page
3. Make sure you've not set "Yes" the "Posts must be manually approved" option in the Dashboard > Forums > Tools > Antipsam Tab
4. If the Akismet plugin is active, please disable it. The user email could be in the Akismet black list.
5. Decrease the suspicion level for topics and posts to 10, 10 in the same Dashboard > Forums > Tools > Antipsam Tab