I hope you can help me, I've been struggling with getting this feed to mailchimp with the images for awhile. My blog images are quite large, so I created another image size in the Functions.php file of 500x262, I regenerated the thumbnails and tried again, but the image in the MailChimp RSS campaign is still too big. I created a new campaign, same deal. Cleared the cache with shift+refresh, no change. When I look at the feed using the Chrome plugin you suggested, there aren't any images. So, I'm completely stumped. Some possibly useful info is that I created the image 595 wide the first time, and it didn't work, so then I dropped it all the way to 500 wide. Could something be *stuck* at that size?
Here's my feed address: http://irmoyoga.com/feed/
Hope you can help!
Thanks,
Fran
https://wordpress.org/plugins/featured-images-for-rss-feeds/