I'm using Outlook 2010 against Exchange 2007. Emails I compose sometimes get stuck in the Outbox with date "None" as shown below. These emails never leave the outbox unless I delete them and recompose. Sometimes the problem happens again until I restart the client.
Additionally, if I open a good (one with today's date) email from the outbox and then send it, it too gets dated "None" and never gets sent.
Best Answer
When I've seen this issue it's been because the 'delay delivery' option has been set to 5pm that day (even though the user has not set this option). You can't clear it (it re-applies) so the short term fix I've been using is to set it to 1 minutes time then the email is sent! Still looking for a proper cause/fix though...