I know about this, and about Postmark great deliverability, but the greylisting some companies use is naive and doesn't care about reputation: if you are a new

I know about this, and about Postmark great deliverability, but the greylisting some companies use is naive and doesn't care about reputation: if you are a new sender, you to have wait 5 minutes and retry, whoever is sending (Postmark or Mailgun).