Invalid api key


#1

{"status":"error","code":-1,"name":"Invalid_Key","message":"Invalid API key"}


#2

This course is outdated.

Make sure that you have enabled Mandrill in your Mailchimp account, read more -> http://kb.mailchimp.com/mandrill/add-or-remove-mandrill

And if you have generated API key long time ago it might be a good idea to create a new one.