[Security issue from Hakiri](https://hakiri.io/projects/440c13579ad439/stacks/4516a1e56fde26/builds/218cf04dc881d6/warnings/f9bbd02c2774d1): Render path contains parameter value in app/controllers/mailpreview_controller.rb
Security issue from Hakiri: Render path contains parameter value in app/controllers/mailpreview_controller.rb