I think the "it is one line of code" needs to be challenged. If you want a reliable, white-listed mail service, it is a whole bunch of upfront and ongoing work

I think the "it is one line of code" needs to be challenged. If you want a reliable, white-listed mail service, it is a whole bunch of upfront and ongoing work with postmasters to deliver a high successful-delivery rate service to your users. And that's just one example.