[communication/send-(templated-)email] Confusion around Mailchimp × Mandrill

[jnv]

Currently both of our transactional profiles provide map for the mailchimp provider, which is confusing for users unfamiliar with Mailchimp's offering.

I just got from a support call with user who tried to use the Mailchimp map with Mailchimp's API key and was getting Invalid key error. The solution was to navigate to Transactional Email in Mailchimp's Dashboard and enter Mandrillapp dashboard.

Apparently the original intent behind the mailchimp provider was to respect that it's a single company and product. However, this seems to be confusing and could even turn problematic with other, Mailchimp-specific map.

My suggestion here is to introduce a new mandrillapp provider and change existing maps for Mailchimp to use that provider instead.

Before we do that, make sure that Mailchimp's APIs require a different API key for sure.

[jnv]

For the record, Mailchimp's and Mandrill's APIs require different keys.