How to configure to automatically designate a post's image as a "featured image".

I have two questions related to automatically designating featured images:

1) I have several sites with autoblog setup, where the imported images are not being designated as featured images. I'd like the images to show up in the "subscribe by email" content, but have not been able to get this to occur, as the images are not automatically designated as featured images within the autoblog import. Have I missed sometime, and/or is there a work around for this situation?

2) I have several sites where instagram automatically posts images to the blog. I'd like these images to show up in the "subscribe by email content", but don't know how to automatically designate the images as featured images. Is there a way to do this?

Any help appreciated!