Interesting situation with one of our end users. Yesterday, she sent an email to four recipients and then immediately shut her computer down. All copies of the email were confirmed to have been received by each of the recipients at that time. However, when she logged on this morning, a second copy of the email was received by each of the same recipients. The sender still only showed one instance of the email in her Sent Items from yesterday afternoon. We speculate that the email might have been in her Outbox when she shut down for the day and if so, it would still have been in the Outbox when she logged in again this morning, thus telling Exchange to send the mail again. However, this does not explain how the email was sent successfully the day before and still exist in her Outbox.
I've researched and found many articles on emails getting stuck in the Outbox or Exchange sending email twice. None of what I've reviewed seems to provide an explanation for this particular occurrence. This appers to be an isolated occurrence; as far as I can tell this has not happened previously with this particular user.
End user's client is Outlook 2007 and server is Exchange 2010.
If anyone can provide some insight into possibilities, I'd appreciate it. Thanks!