You can add the agents who would receive the moderation emails and would have permissions to moderate Forum Topics. To add agents to moderate your forums, please navigate to Admin > Channels > Portals > Settings > and choose an option from the list. If you choose "Moderate all topics and replies" or "Moderate topics with external link", you would have an option to choose the agents who would receive moderation approval emails.
These agents would be able to moderate any new topic, based on the option chosen, from under Dashboard-->Forum Moderation, only after approval would the topics get displayed on your portal.