1. Go to your dashboard and click email posting icon
2. Create your email address to post
3. go to setting – email and mobile
4. change the posting option to save email as draft post
5. from your Facebook message, create message to your custom email blog posting address, and the message automatically saved as draft post, and you may edit it later to erase you custom email blog posting address before you publish your post to prevent misuse of spammer!
6. And there you go! :P