The safest thing you can do is NOT open the attachment from people you don\'t know, never remember making contact. What if it comes from friend? Simply send a new e-mail back to your friend asking him/her if he/she sent the e-mail with the attachment.

Getting Microsoft e-mail with attachments that are supposedly patches to the system's kernel? General rule is that companies like Microsoft will not send attachments with fixes, rather they would send you to the website. Not sure if the e-mail is valid, check out this link.