Have you ever received an email with an unreadable file attached called "winmail.dat"?
This is an attachment sent to you from a person using Outlook. They have sent their email using a Rich Text Format or HTML Format. The problem is, you must have Outlook to read that attachment.
Solutions?
Install Outlook and use it to view the email.
* or
Reply back to that person and ask them to resend the email as Plain Text.