Could be a Read Receipt.

" wrote:

I did a search first, but couldn't find anything that applied to me.

We use Outlook 2003 and until today everything was fine. Starting
this morning however, my personal Inbox shows that I have one unread e-
mail, but there is nothing in there. I have done an advanced find on
my entire Mailbox and tried using the Search Folders for Unread Mail
with no luck. This is really annoying because no matter how many e-
mails I get, it continues to show just the one unread mail.

Any help would be great,

Richard