After saving to Aras, the connector displays a small pop-up message in the lower-left corner of the Office application. This message is displayed for Outlook as well as the other Office applications, but is particularly useful for Outlook because it is how you find out the Document number that the email message is saved to. If you click on the hyperlink in the message, it will open the form of the Document in Aras.
This works in Word, Excel, and PowerPoint as well, but in those applications you have the ribbon to show you the Document number. In Outlook this is the only place that this information is presented to you.