Junk mail folder
The junk mail folder or spam folder is a tool used for filtering electronic junk e-mail out of a user's inbox on his or her private or commercial e-mail account. Most major e-mail clients include junk mail folders for their users due to the increasingly high volume of junk e-mail in the 21st Century. A junk e-mail folder attempts to detect junk e-mail and electronically file it into the folder before it appears in the user's inbox.
The junk mail folder allows you to see what e-mail is junk and what is not. To determine what is junk an e-mail program may look at what time the e-mail was sent, the sender's e-mail address, and the content of the e-mail's message. If any of these areas look suspicious the filter moves the e-mail accordingly.
Depending on the e-mail service you sometimes must "teach" a junk mail folder what e-mail is junk and what is not. You can accomplish this by highlighting an e-mail in the junk mail folder and clicking the "Not Junk" option. This terminology may different depending on the e-mail client. By doing this the filter learns what is and is not considered junk mail.