Once you stop the send and receive, the Outbox will be visible (3) in the folder list. If you use Outlook 2011 and don't want to send the message or its stuck for other reason: Close Outlook 2011; Hold the Shift key down while reopening Outlook. Go to Outbox and delete the stuck message. And Outlook for Mac makes me sad. That’s because, when compared to its Windows counterpart, Outlook for OS X (aka Outlook 2011) is an underperformer. Maybe it’s because the Windows version was built in the same shop as the Exchange service. Or maybe Microsoft has an understandable bias.
I’m seeing more users complain that meeting invitations won't send. Email sends just fine, but meeting requests are stuck in the Outbox. Because some items send, it's not the SMTP server or authentication issues, both of which are the usual suspects when mail won't send. While certain add-ins are known to cause stuck messages, these recent incidents are caused by the Norton Antispam Outlook Plugin. To disable the add-in in Outlook 2010 or Outlook 2013:. Go to File, Options, Add-ins. Click the Go button at the bottom of the window.
Find the Norton Antispam Outlook Plugin and deselect it. Click OK and return to Outlook. The meeting requests should send. If not, open each meeting request and click Send.