Like Internet-based and stand-alone email programs, Microsoft Outlook lets you send messages, including ones with attachments, to individuals as well as groups of people. Email messages are composed in a word processing-like interface then sent via your computer's Internet or network connection. Each outgoing message is sent through a variety of channels and servers before reaching its recipient.
The Microsoft Outlook Outbox is a temporary holding folder for outgoing messages composed within the program. The folder holds your messages until you click the "Send/Receive" button or automatically if you have Outlook set to send outgoing messages automatically. The Outbox folder is listed in the left pan of the Outlook program dialog box and is accessible by clicking on the folder's name.
Outbox to “Sent” Folder
After a message is sent from the Outbox, it is then moved to Outlook's "Sent" folder, which is also listed in the left pan of the Outlook program dialog box. You can access the "Sent" folder to see if a specific email or group of emails has been sent.
Each version of Outlook includes an Outbox as well as a "Sent" folder. Large messages, containing attachments and/or graphics, within the folder may take an extended amount of time to process and send the messages. Once the large message(s) is sent, it will move immediately to Outlook's "Sent" folder.
Outbox Issues – Offline and “Send/Receive”
One problem you may encounter with outgoing messages in the Outbox is the messages failing to be sent from the folder. One or more messages may be stuck due to a problem with your computer's Internet or network connection not being "Online." If your version of Outlook processes emails through Microsoft Exchange Server and the program is offline — in Cached Exchange Mode, one or more messages may not be sent from the program's Outbox. If you are using offline folders or a remote service, this may keep messages from being sent. Another reason for a message not being sent is if you open the message from within the Outbox for editing and you forget to click "Send/Receive" to process the email.
Outbox Issues – Rules
Another reason why messages are not sent from the Outbox is due not having certain rules set within Outlook telling it to only send mail at a specific time or if a certain set of parameters are met. Parameters include not sending mail until you manually click the "Send/Receive" button, only sending outgoing mail at a certain set hour or only sending messages when a command is sent to close Outlook.