I find it pretty hard to know what are the variables (some examples:
message.id, recipient.firstName, delivery.label, etc) available that can
be used inside email deliveries. I was wondering if an exhaustive list
existed, but can't find any in the online documentation.Moreover, for
debugging purpose, I think it could be really useful if we could use
some javascript to send some test email deliveries which would output
all the available variables (their key and value). It could look like
how JSON...