Hi,

We're using SendGrid with a dedicated IP address, and I must say we have a nearly 100% delivery rate.

I do just want to note - you can use any service that supports SMTP delivery using the built in SMTP option. You don't necessarily need a specific API to send emails. 

(This post is not discounting the rest of the conversation, I just want to be sure anyone who comes across this realizes you can still use Sparkpost or whatever else via SMTP if you want)