Number of Incidents Created by Source Unique

Content

I'm needing to create a report that counts the number of incidents created by source.  The sources are AAQ, Phone and Email.  BUT the email is not using the techmail source and incidents are not being created by email but the agents are selecting Customer Entry Email when they manually create the incident.  How would I get the number of incidents created by email but only the 1st entry of email when the incident is created and not any other emails that are sent out via a response or by a rule.  Any ideas or help would be appreciated.