Also, can we use ory kratos without the smtp server? I know the configuration is mandatory in

kratos.yml

, but I want to use ory kratos for quick prototyping and I don't want to deal with the mailer right now

The mailslurper container that's already in that docker compose is all you need in dev. It's an ephemeral & catch-all inbox for any sent mail for dev purposes. If you visit that container in your browser, you'll see any mail that kratos meant to send

I see. But can I use mailslurper in production as well? If not, what may I replace it with? Any recommendation there?

postfix?)

I use sendgrid with mine