Frequently, I need to filter for only sales emails sent via SFDC or only those sent via Outlook, but not both.
The various sales email filters could have a constraint for this based on the fact that Sales emails sent via Outlook have a Email GUID in the format - mailingDef:18559:artifactId:121177 and sales emails sent via SFDC have a Email GUID in the format - f7c0431e-69c3-494b-ad3a-063066acae78-290 and a separate Artifact ID.