By default, Outlook will send your outgoing messages to the Outbox allowing you to have more control of when you actually send them out of the Outlook client to the Internet where you won’t be able to make any changes after they are sent. This way you can compose and send multiple emails and then make sure they are correct before finally sending them out.
Many people don’t like this extra step and prefer to have their email be sent out to the Internet right away after pressing send within the new email window. This option can be changed very easily so Outlook will send the email right away after pressing the Send button. The steps will vary depending on what version of Outlook you are using.
For Outlook 2010 and up click on the File tab and then choose Options. For Outlook 2007 and 2003 go to the Tools menu and then click on Options and select the Mail Setup tab. Now find the checkbox that says Send immediately when connected, put a check in it and click on OK.
Now whenever you click on the Send button from within a new email it should immediately send it out and not put it in your Outbox. Just keep in mind that you lose the option to go back to your Outbox and make any changes to your email before sending it when you choose this option.