I think many people don't realize...the 'from' part of any email you receive can be faked...almost as easily as faking the return address on a regular letter. 

The email's header information has details about where it really came from, but to expand on the analogy above, it's roughly the same as seeing that the postmark on the envelope doesn't match the city of origin...and in reality, even that information can be forged in an email. 

Even if you receive an email from someone you might normally expect, if their name/address don't look right in the 'From' field, be suspicious.  Be wary of extra quotation marks, spaces, or other punctuation in their details, because it might not really be from your friend.