Zimbra offers a Blocked Senders list for email addresses and domains (like "@spam.net") To add one of these to the list, use the following steps: 1. Login to Webmail at http://mail.ias.edu 2. Click the Preferences button near the top of the page. 3. Click Mail on the left sidebar. 4. Scroll down to Spam Mail Options. 5. Enter the address or domain to be blocked into the field under "Block messages from:" and click Add. 6. Click Save near the top of the page. You can also use the "Allow messages from:" list to make sure that you receive mail from certain senders or domains.