Q. When I send an email message, it doesn't always leave my Outlook Outbox. My settings are all correct, so why is this?
A. Normally when you send an email, it goes into your Outbox with the recipient's name and subject displayed in a bold italic font and the icon is a closed envelope. Sometimes, if you look in the Outbox, messages waiting to be sent lose the bold italic attribute and the messages won't be sent. You'll need to open the messages, switch to another folder and click Send.
This behavior might be due to some Outlook add-ins. These add-ins touch the message by using the Outlook Object Model, which causes the message submission to abort. The add-ins that cause this problem read the message and inadvertently mark it as read, and since Outlook won't send a read message, it remains in the Outbox until you open the message and resend it.
The Send to OneNote from Outlook PowerToy and early versions of the Business Contact Manager (BCM) for Outlook are two popular add-ins that cause this behavior.
Once you've verified you have the most recent version of the add-in installed and the problem still exists, the easiest fix is to stop opening the Outbox. If you need to look at the items that are waiting, use Find or Advanced Find, or create a Search Folder (but don't preview messages in the Reading Pane) and include the Outbox folder in the search.
If you can’t live without looking in your Outbox, your only other option is to identify the add-in and disable it. On the Tools menu, click Options, click the Other tab and click Advanced Options. Next, click COM Add-Ins to check for your installed add-ins. Disable the add-ins and re-enable them one at a time to test them.
BCM, and possibly other add-ins, aren't listed in the COM Add-Ins list, so you'll need to check the registry for the following subkeys:
Export the subkeys, and then change the LoadBehavior value to 0 in order to disconnect an add-in. Restart Outlook and test.
Caution! Incorrectly editing the registry may severely damage your operating system, requiring you to reinstall it. Nobody can guarantee that problems resulting from editing the registry incorrectly can be resolved. Before editing the registry, back up any valuable data.