Set a custom image size
Design the image size displayed in emails.
Customize your own size for RSS images.
The standard plugin provides size options from your site's media settings, which cannot be edited through the plugin. This Premium feature provides an additional option to custom define a size.
How To Use It
1. Go to our plugin page from your WordPress dashboard, located in the left sidebar. The feature is set to thumbnail size by default.
2. After upgrading, the "custom" option will show up from the drop down menu in the Premium plugin. Additional fields will appear to enter your own desired size in pixels. Both width and height must be defined.
3. Save your settings.
Now your custom image size will have been added as a new size to your website global "Media Options". This means that any new images added to the media library moving forward will have the new size option generated by WordPress. For existing images uploaded to your media library prior to now, the new size will not be created until you complete step four to regenerate thumbnails.
4. For the new size to take effect on existing post images, you must Regenerate Thumbnails. You can use the recommended plugin we've linked up or another of your choice that accomplishes the same.
5. View your RSS feed to confirm the new size is being output to your preference. For RSS email, send a test email.
If you are not immediately seeing the option take effect, clear your website cache or refresh your feed with the third party service being used to display your RSS content.
Read: Are you using Mailchimp RSS email with a non-https site?