Hey Lynne! Although your images are larger than will work well for email, I don’t think that’s the cause of what you’re seeing. WordPress 4.4 introduced responsive images, which is awesome. However, the way it works is by adding special markup to each image, and I’m finding that this causes issues in feeds, especially in feed readers (like Feedly, although I hear they are trying to work on a fix from their end) and the MailChimp previews. I believe that if you send yourself a test email, the images will show in the email.
Personally, I think that the responsive image functionality (at least for now) needs to be removed from the RSS feeds. The latest version (3.1.0) of this plugin handles that automatically for you, so yes, I think it would help you out, plus it would give you well-sized images for MailChimp.
If you’re not as concerned about that, and just want to try removing the responsive image functionality from the feed, you can try adding this code to your site (in your theme’s functions.php file, or wherever you keep similar code):
add_filter( 'wp_calculate_image_srcset', 'prefix_remove_srcset_from_feed' );
function prefix_remove_srcset_from_feed( $srcset ) {
if ( is_feed() ) {
return false;
}
return $srcset;
}
If you go the code route, please make sure your file(s) are backed up, practice safe coding, etc. etc. etc. I do not know if this is the best way to handle the issue, but it does seem to be working for me.
I believe that the responsive images team is still looking into this for WordPress Core, but disabling this in the feed is the route I’ve opted to take for the time being. Hope that helps!
