When you type an e-mail alias, the automatic completion
feature may not correctly resolve the address to a name in the display name
This behavior can occur if someone you send e-mail to has
no display name and a blank entry is added to the name cache.
To resolve this behavior, rename the .nk2 files that are
associated with your profile. The file names have an .nk2 extension, for
has confirmed that this is a problem in the Microsoft products that are listed
at the beginning of this article.
For additional information, click the following article number to view the article in the Microsoft Knowledge Base:
How to reset the nickname and the automatic completion caches in Outlook