You can still forward email to an off-campus address, but you'll have to set that forward up in Google Apps  (not Account Center). You may even want to give Google Apps a try (we think you'll like it!) and just start using it on your migration day!
To setup your forward: 1) Login to your HSU Google Apps account (mail.google.com/a/humboldt.
If you had a forward in Zimbra and don't set up a forwarding address, your mail won't be lost (it will be waiting for you in your Google Apps account), but it won't arrive in the account you're used to checking.