I have a client with QB Enterprise 2012. Same issue, no Outlook option in "Send Forms". I tried everything suggested, nothing worked. Finally I uninstalled Office365 and reinstalled using the 32-bit version of Office instead of the default 64-bit Office version that is usually installed nowadays and bingo! the Outlook option reappeared in "Send Forms" Preferences. Hope this helps. To get the 32-bit version after uninstalling Office and rebooting, log in to Office.com and on the drop-down for "Install Office" click "Other Install Options". On the next screen in the lower left click on "Apps and Devices", then in the middle of the resulting screen you'll see the drop-down menu for "Version" with 64-bit selected by default. Select "32-bit" instead of the 64-bit version and when you click "Install Office" it will download the 32-bit installer, then click that to install. Hope this helps.