All the fields actually displayed by regular email clients can be spoofed. To work out where the email actually originated you need to backtrack through the headers which usually aren't shown. Each mail relay adds it's own info to the top of the header trail as it passes through to the final destination and some (but not all) will check that the previous relay/server's ip or domain is resolvable. They don't (and can't) check the From: address for various reasons. It could originate from some department machine sat on an company's internal-only network with whatever name and address they've chosen for it. Or, it could be a task-id that has no real user behind it.
There should be an option on your client to see the whole message including headers for each email. For Thunderbird it's More-->View Source. On gmail it's More-->Show Original.