Setup

So you want to have a website

Mailgun

Pikapods:

Environment

mail_from: postmaster@mg.dancollinsuk.com
mail_option_service: Mailgun
mail_options_host: smtp.eu.mailgun.org (the eu is always not mentioned by US blogs)
mail_options_auth_user: postmaster@mg.dancollinsuk.com
mail_options_auth_pass: 12345678901234567890123456789012-12345678-12345678

Cloudflare:

Now the thing to get your head round is, that the http:(nowww)://blah.. sends it to http://www.blah.

Cname: dancollinsuk.com
Target: www.dancollinsuk.com

Cname: www
Target: liberal-chamois.pikapod.net