Since this is open since almost 7 years now, I created a pull request to solve this issue FIX: Resolve upload:// URLs in plain-text emails - Pull Request #45399 - discourse/discourse - GitHub
Hope you can add it soon.
Since this is open since almost 7 years now, I created a pull request to solve this issue FIX: Resolve upload:// URLs in plain-text emails - Pull Request #45399 - discourse/discourse - GitHub
Hope you can add it soon.