UPS was not able to delivery your package and your claim is in this attachment.
Would you believe that? You shouldn't! Think about it for a moment...how did UPS get your email address and attach it to a package someone may have sent you?
Tis the season for Holiday cheer and a rise in malware infections. ESET's security blog has more details on the types of email and malware that prey on the goodwill of Christmastime.