Do NOT open an email attachment unless you were specifically expecting that file from that person. If you are at all uncertain, contact the sender and ask them if they meant to send you the attachment.

An email attachments is NOT safe just because it appears to come from someone you know! You are actually more likely to receive an infected attachment from someone you know because if that person's computer is infected, it is likely sending email to everyone in that person's email address book (a.k.a. you).

Don't be fooled! Often the sender of an infected message is faked. This is a fairly recent trick called "social engineering" -- the virus picks up email addresses found within the local network and puts those addresses in the "from" box. They hope you will be more likely to open the attachment because it looks like it is from someone within your community and therefore appears more legitimate.