refs: #13380
- this is to replace i18n.t with tpl because i18n.t is deprecated
- Replaced i18n.t with tpl helper in email-post.js
- Replaced i18n.t with tpl helper in email-preview.js
refs https://github.com/TryGhost/Team/issues/990
- Relying on uuid instead of slug makes the posts less discoverable and partially soves discoverability through overriden robots.txt files
refs https://github.com/TryGhost/Team/issues/899
- The internal API is needed to be able to fetch email-only posts through email router. The concept is similar to Preview API with a difference that only posts with `sent` status are accessible and there is content-gating present.
