Featured image everywhere but email

Thanks for any and all help. I’ve been trying to fix this issue for nearly a month now. The featured image for posts works just fine EVERYWHERE except in emailed posts. In those, it grabs the site logo. So I delete the site logo and then it used the Jetpack logo. I even installed the FIFU plugin and NO PROBLEM with using off-site images. Except in email. Social media? The images are fine. But I simply cannot get the featured image to show up in email. Please help!