refs https://github.com/TryGhost/Team/issues/1550
- Updated email template and seder options to use the settings specified for the related newsletter
- Falls back to the default newsletter, and uses the default newsletter settings for the publishing preview because we only assign a newsletter at the point a post is published
Co-authored-by: Thibaut Patel <thibaut.patel@gmail.com>
Co-authored-by: Matt Hanley <git@matthanley.co.uk>
