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.
Some users report that disabling the add-in then repairing the Office installation before re-enabling the add-in fixes the problem.
If you are having a problem with your mail not sending but aren’t using Norton Antispam, check your add-ins. Other antivirus and antispan add-ins, as well as iCloud, have been known to cause problems sending Outlook items.
Published November 11, 2013. Last updated on February 25, 2014.