What's special about the Resend API? Sparkpost has allowed scheduling emails for many years.

Slightly off topic but the trend where websites are completely BLACK, even though I don't have dark mode on makes me quit them instantly. It's hard on my eyes, maybe it's my screen, maybe it's my eyes but I have a hard time reading it.

Given all the limitations this API has, including "Emails can be scheduled up to 72 hours in advance.", the use-cases they mention like scheduling an email for an event or a weekly digest, will still require using a Job Queue in your application (like Oban for Elixir), mostly negating the managed-service aspect here.

Another issue is, when using a job queue, you may check at the time of sending the email whether you still want to send it. With queuing it, you'll have to periodically check for all scheduled emails whether you want to cancel any.