Items stay in the Outbox and never clear

If items are not italicized

(If the email is italicized then jump to the next section below.)

If someone sends an email "as" someone else, the email will be sent but the item will remain in the outbox The fix is easy - in Outlook you need to enable cache mode.

In Outlook 2010:

• Click on File
• Click on Account Settings button --> Account Settings...
• On the Email tab, double-click on Microsoft Exchange
• Select the option Use Cached Exchange Mode
• Reduce the slider to download only email up to 2 years
• Click on More Settings → Advanced
  
• Remove the check mark beside "Download shared folders"
• Click OK, Next and Finished to complete the change
• You will need to Restart Outlook for the change to take effect.

In Outlook 2007:

• Click on Tools --> Account Settings 
• On the Email tab, double-click on Microsoft Exchange
• Select the option Use Cached Exchange Mode
• Reduce the slider to download only email up to 2 years
• Click on More Settings → Advanced
  
• Remove the check mark beside "Download shared folders"
• Click OK, Next and Finished to complete the change
• You will need to Restart Outlook for the change to take effect.

Items are italicized

If the message is italicized it means it has not been sent There can be two reasons for this:

You are over quota

• Look for a small "error" listed on the bottom bar of your Outlook window Click on that error and it will probably say that you are over quota Please see this page for additional info.

The email address is not in the correct format for Outlook

In Outlook 2007:

• Go to the message in the sent items and double-click on it
• Double-click on each email address and check the mail type  If the email type is mailto it will not send
• Click on the Internet Type button and this should change the mail type so it now says SMTP (greyed out)
• Now close the email address and hit the re-send button The message should be sent immediately.