You can query it on the following lines
SELECT DATE_FORMAT(timestamp, 'yyyy-MM') AS rolluptimestamp, SUM( CASE WHEN _experience.customerjourneymanagement.messagedeliveryfeedback.feedbackstatus = 'sent' THEN 1 ELSE 0 END) AS deliveredcount FROM cjm_message_feedback_event_dataset WHERE _experience.customerjourneymanagement.messageprofile.channel._id = 'https://ns.adobe.com/xdm/channels/sms' GROUP BY DATE_FORMAT(timestamp, 'yyyy-MM') ORDER BY rolluptimestamp desc;
Alter the channel Id accordingly for direct mail as https://ns.adobe.com/xdm/channels/direct-mail
Reference - https://experienceleague.adobe.com/en/docs/journey-optimizer/using/data-management/datasets/datasets...