You should always be careful when you receive email from social network. Take following email as an example:
[REDACTED] commented on your Wall post.
[REDACTED] wrote: "you piece of ****!!!"
See the comment thread
Reply to this email to comment on this post.
The Facebook Team
If you are careful enough, you will notice the trick of the poor disguised email address "email@example.com". This is common trick exploit by cyber criminals to deceive victim and make them believing the message is from the official organization.
Similar trick will also be take to fool you, for example, you have a friend with the email address of firstname.lastname@example.org, while the scammers take email@example.com to send you email with malicious content and make you believe the email is from you acquaintance.
While in this email, once you click on the "See the comment thread" button, you will be redirected to a website hosting a malicious iFrame script instead of real facebook page. The malicious script will run automatically on your computer and your computer is under great danger.
Firewall and anti-virus program are always necessary to protect computer security.