How to make a very dynamic mailing list with MailChimp and Ruby on Rails?

Question

Ruby on Rails

I just can’t figure out the API and the meaning of MailChimp in general.
Installed Gibbons. Set up. I tried it, it works.
Task: By pressing a button, send letters to 20 specific users (each time different). At the same time, the letter template can be changed on my resource. The template contains tags by which you need to insert data.
For example, the template "Hi {{user_name}}" And each of the 20 users will receive an email with their name. Doing this through the Rails mailer, I wouldn't bother at all. However, they require through MailChimp. Tell me please.
In a draft version, I sketched an approximate scheme, but I am almost sure that this is nonsense and will take a very long time to complete:
Create a list with these 20 users.
Create a campaign and send to that mailing list with a template that I'll pass along.
Delete Campaign
Delete List.

Answer 1

ActionMailer + mailchimp/mandrill.