DefectiveYeti has a great post on You say Tomato. I had a very similar things happen to me before.
My bossed asked me if I got a customer to sign-off on a document. I said they didn't have a fax machine so I couldn't get it to them for them to sign.
Boss: Why don't you just mail it to them.
Me: How are they going to email me back a signed copy?
Boss: Postal mail...