I have tried adding %{first_name} or %{current_user.first_name} to yml file and to the view. I get error,
ActionView::Template::Error (missing interpolation argument :first_name
How can I add "name" has invited you! instead of "Someone has invited you" which is the default and is likely to be seen as a spam?
You should be able to find the user by the invited_by_id
@user = User.find(resource.invited_by_id)
Here is a link, Open the link and scroll up above the heading Sending an invitation after user creation