I think we'd get a simpler, more robust :trollface: result by just using the `RobustEmailParser` and not defaulting to the regexp matching. This would also remove the need to add the option to override the parser_class.

I assume your reason for not doing this by default was to not require a dependency on `Mail`, is that correct? If that's the case, Rails (via ActionMailer) already has that dependency, and we depend upon Rails as Griddler is an Engine, so there's no actual added dependency.