If the Request Confirmations setting is checked, a Notice is displayed in the following cases:
When you have text or attachments in the Compose window, and you select Clear on the Compose window control panel, a message is displayed asking if you really want to clear the Compose window.
When you have text or attachments in the Compose window, and you quit the Compose window, a confirmation message is displayed asking if you really want to quit.
When you have made changes to a message in the View window, and you then display a new message, unpin the View window, or receive new incoming mail, a message is displayed asking if you want to save the changes.
If the Request Confirmations setting is not checked, any editing changes in the View window are automatically incorporated without notification. If you remove or change the From header of a message. The message that lost the From header will appear to be lost. You can find it appended to the previous message.