In an email client such as Microsoft Outlook or a webmail service, mail is organised into folders that each represent a stage in a message's life cycle. The Outbox is the temporary staging folder for messages on their way out — its correct description is that it temporarily stores emails that are queued for sending.

Here is what actually happens when you press Send:

• The composed message leaves the compose window and is placed in the Outbox, where it waits to be transmitted.
• The client then contacts the mail server (typically over SMTP) and hands the message over. A message may sit visibly in the Outbox for a while if you are offline or the connection is slow.
• Once the server confirms successful transmission, the message is moved out of the Outbox and into the Sent folder.

This clears up the other options, each of which describes a different folder:

• Receiving incoming emails is the job of the Inbox, not the Outbox.
• Emails currently being drafted are saved in the Drafts folder, which holds unfinished, not-yet-sent messages.
• Emails that have been successfully sent reside in the Sent folder — the Outbox only holds them before delivery, never after.