Unfortunately, Blubrry doesn't support a global setting for adding any prefix URLs. However, you can add them on an episode level.
- When adding a new episode, scroll down to the area where you link your "Media URL" from Blubrry.
- You'll see an URL looking like: http://media.blubrry.com/yourshow/xyz.mp3
- Add your unique Podder prepend to this link by replacing the "http://".
- After you add the Podder URL the link will look similar to that: https:/podderapp.com/235345/media.blubrry.com/yourshow/xyz.mp3
- Click save & Publish
- You can go back and edit already published episodes. It will have no negative affect on your podcast feed.
If you are using more than 1 prefix URL at the same time you will have to separate them with a forward slash, and remove the https:// of subsequent URL's after the first prefix.