The AutoComplete feature does not function as expected in Outlook 2010 when you use the "Send as Attachment" command

KB Article: https://support.microsoft.com/kb/2589404

INTRODUCTION

Assume that you use the Send as Attachment command in a Microsoft Office 2010 application to send a file.
When you type the name of a receiver in the To field, the AutoComplete feature does not function as expected in Microsoft Outlook 2010.

Note This issue occurs when you use the Send as Attachment command in the Office 2010 application before Outlook 2010 is running.