Error The Operation Cannot Be Performed Because The Message Has Been Changed Description: The messages affected are the ones that Outlook has automatically saved a draft of while you are editing them. If you create a new message, type quickly, and send it before a draft is saved.

The message will send fine; however, if you take time to compose the message and Outlook saves a draft for you, the message "The operation cannot be performed because the message has been changed" occurs when you try to send it.

The message that Outlook thinks has changed is the one in the drafts folder, and the send fails because it cannot delete the draft as part of the send operation.