Hello Andrew,
By default, Easysocial will delete the file once it has uploaded to the remote storage (without any setting to change the behavior). Then, Mark has added the option to choose whether not to delete the original file after upload which, in my opinion, has defeat the purpose of having remote storage.
However, I've consulted with the team. Currently, there is no fix for this yet. We will push this in the next major release of Easysocial where Easysocial will upload the photo to the amazon on the fly. Means, the time user post a photo, it will directly upload to the remote storage without waiting for the cron to execute.
For now, we will provide a temporary fix where no image will be included in the email if the remote storage option is enable. Is it okay for you?