e-Newsletter: How to set it up and which mail distributer you would recommend?

Hi, I hope you are fine

we would like to setup e-Newsletter - any links to tutorials of the newest version? - and we would like to know from the community and the devs what they would recommend for sites which currently contains only about 2000 - 5000 email addresses.

Our template which we use provudes a template for the mailchimp but how to change so that it is actually using e-Newsletter instead?