Emails

• The theory that Facebook deletes your account after a period of inactivity is usually perpetuated through forwarded email messages. Although you'll never get an email from Facebook itself, it's common to receive forwarded messages from friends who have been duped into thinking a message they receive is real. They then forward the message to their friends and spread misinformation.
  
  

Message

• The hoax message that many people receive warns them that if they don't forward the email to at least 15 friends, their Facebook account will be deleted. The message is a classic example of a chain letter, threatening undesirable results if the message recipient doesn't forward the email. In some cases, the message is signed as though Mark Zuckerberg, the founder of Facebook, wrote it.
  
  

On Facebook

• Occasionally, you'll see a chain message on Facebook. Though it's unclear where these chain messages begin, you may occasionally see a post on a friend's wall saying that Facebook will delete her account if she doesn't post this message on her wall, and she's encouraging her friends to do the same. When people see this message, they may also post it on their walls, helping the urban legend spread.