Paywall editor automatically removes subject of mailto: links

When you add a text in the Paywalls editor you can add a mailto: link in the text. Is there a way to include the subject in that link? The editor seems to not store any parameters of the mailto links.
Along the same lines it would be super nice if instead of creating a whole different offering, paywall and targeting for iOS and Android just to have one link be different there were a way to just provide a different link for each environment.