Ask HN: Email delivery service that works?

Are they any premium services that can just actually get an email to my customers?

I've got about thousands of signups that haven't gotten an email in 6 months because it's such a hassle trying to actually get them delivered. The product they care about is finished being launched in just 12 days. It is insane to me that email service providers like AWS and sendinblue actually require you to "warm up your ips" as though you were a spammer...

I'd pay thousands to actually get delivery. Is there some white glove VIP service somewhere?