I don’t understand how $0 per outgoing email with MailChannels will cost more than $0 for a million emails. For incoming emails, Cloudflare Email Workers are $

I don’t understand how $0 per outgoing email with MailChannels will cost more than $0 for a million emails. For incoming emails, Cloudflare Email Workers are $0 per email and SendGrid is also $0 per email. We only pay for the cost of the Worker with this setup.