Is there a way to customize image sizes beyond the 'thumbnail', 'medium', and 'large' options? I tried setting width and height in the <img> tag within an RSS file, but it didn't work. Could it be a nested quotation marks issue as shown in this answer: ?
When attempting to insert a post's featured image into a custom RSS file using PHP, specifying image size through mailchimp RSS-to-campaign editor didn't seem possible.
<?php while(have_posts()) : the_post(); ?>
<item>
<title><?php the_title_rss(); ?></title>
<link><?php the_permalink_rss(); ?></link>
<?php if(get_the_post_thumbnail()): ?>
<media:content url="<?php $image = wp_get_attachment_image_src(get_post_thumbnail_id($post->ID), 'medium'); echo $image[0]; ?>" medium="image" />
<?php endif; ?>
I found that changing 'medium' to 'thumbnail' was successful for altering parameters, but substituting it with 'width="600px" height="300px"' reverted to original image sizes instead.