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One thing you can do is to click the "JunkSpam" button in your email program when you receive a spam email message. This will train Zimbra Gmail to help keep these messages out of your Inbox. (It's not foolproof, but it helps!)
As an example, here is an email message that was delivered to lots of folks on campus in May, 2011. This message has been annotated with a number of ways to indicate that it was NOT a legitimate message and did not originate from Carleton. Note that more sophisticated scams will appear more convincing.