CiviMail problem; possible Cron Error: EntityMalformedException: Missing bundle property on entity of type node. in entity_extract_ids()
Turns out that this cron error is unrelated to CiviMail going out. I resolved the problem by changing the group owner and permissions of the /sites/default/files/civicrm/templates_c folder, which was effecting /mail.log. The group permissions was changed to root, which won't work for the mail. 

I am still getting this cron error, but know now that it probably has to do with Drupal alone.