parse_content_type

# File actionmailer/lib/action_mailer/old_api.rb, line 245
    def parse_content_type
      if @content_type.blank?
        [ nil, {} ]
      else
        ctype, *attrs = @content_type.split(/;\s*/)
        attrs = Hash[attrs.map { |attr| attr.split(/=/, 2) }]
        [ctype, {"charset" => @charset}.merge!(attrs)]
      end
    end