I am trying an Email Send through Email Studio on a Sendable DE which has 2 sample records. My email send completes successfully and when I check the status under tracking, it says Completed but "0 Emails Sent".
To debug this, I pulled out a tracking extract for "Not Send" and under the reason column it says "Missing Email Address".
Background on my Setup
My sendable DE resides within the shared DE folder and contains Contact records from salesforce which I update using an SQL query activity from the Synchronised Salesforce Contacts DE in the parent BU. It links to the Subscriber Key using the Id field on Contact record. Also, the sendable DE contains 4 email address fields (which I know is not recommended), with each field containing a alternate email addresses for the contact.
When it occurred to me that I have no where defined which email address to use for the email send, I tried to use the Channel Address Order (CAO) but my sendable DE didn't show up there. Then I learnt that I had to define this DE as a population for it to show up in the CAO, so I tried that as well, defined the CAO for the 4 email address fields but still no luck. My email send still says 0 emails sent.
Now this is the first time I am doing a send on this particular DE and hence the contact records do not yet exist in all subscribers.
Is there something else that needs to be done to be able to do an email send on a data extension? What am I missing or how can I debug this further ?