X-Source and related mail headers

In relation to the Exim server where the option is active, are the e-mails (without the desired headers) incoming/inbound (received in a local Inbox) or outgoing/outbound (sent from your Exim server)?

The X-Source headers may be added only to e-mails that originate from the server using the option; it will not apply to e-mails that are simply received by a server using the option because the receiving system may have no way to accurately obtain the information. Based upon my observations I believe the information added by the X-Source headers is only available to the originating server, such as an account username, a specific program with CLI arguments used, and or other detail that may not always be included in other standard headers.