It's a newsletter platform. What does it mean that you want email delivery off by default? If what you're after is a blogging platform with optional email delivery I'm sure there are countless alternatives out there.
> A Substack combines a blog, newsletter, payment system, and customer support team — all integrated seamlessly with a simple interface. We handle the admin, billing, and tech so you can focus on your best work.
> Substack’s simple system lets you publish to the web, email, and our app simultaneously so you can find new readers and always reach your existing audience.
> Substack helps anyone set up a blog and email newsletter. No tech knowledge is required. Without ads and algorithms to get in the way, you can sustain a direct relationship with your readers and retain full control over your creative work.