@benja-M-1 you're right but this method depends ont the fact that MailerData is filled or not... so, first it should throw a LogicErrorException if MailerData we're looking for is not set because we have to collect data before.

And then it could test the isSpool key indeed... or at collect time ```$data```could be initialized with default values.

@jeremyFreeAgent what do you think?