Morgan Kay

If you use a service such as Feedburner or MailChimp to turn your RSS feed into an email subscription, and the images in your posts are more than 600px wide, the formatting of your HTML emails might be messed up. This plugin lets you resize the images in your RSS feeds.
Version 2.0 has been completely re-written from scratch! It is now more reliable, and works with images from external URLs.

RSS Image Resize

Resize images in RSS feeds so they will fit in HTML emails.

zackdesign

Please let me know via zackdesign.biz if there’s anything broken in your layouts as a result of moving to Bootstrap HTML.
Image Feeds will work in the plugin providing that they use enclosures. If you want you can change the template provided to suit your feed if necessary, though this should work if enclosures are used correctly.
Please be aware that I’ll only be updating this if I need to. Feel free to come on board and contribute!

RSS Image Widget

This plugin provides you with a widget to display images from a feed. It requires Wordpress' SimplePie include.

RSS Image Resize vs RSS Image Widget