Maybe it's a meaningless email from a spammer who is trying to identify and compile "spam traps"? I wouldn't call the number, it's probably some poor guy's number who has nothing to do with this. The email's IP is probably faked and the return email address is probably spoofed. Just be glad you are not the owner of that phone number OR the return email addy being used. You would be getting hate email and phone calls.
The return email address is DEFINITELY faked / spoofed, as one of the "undeliverable" reports just came to me. Somebody has been having a lot of fun spoofing my email address, and I'm not sure how to report it to Yahoo. I've started getting hundreds of bounced email notices over the past few weeks.