Here are our recommendations for managing spam in your Gmail account:
- Check your Google Apps spam trap often, even if you are forwarding mail to another account.
- When a valid message is found in a spam trap, mark it "not spam."
- List as "contacts" those from whom you expect to receive email.
- You can set up a Google Apps filter in which you can specify "Never send to Spam" for particular senders.
- Check IT's page on reducing spam.
For more information, see the Gmail spam Help page.