I liked the article as I once had a similar requirement! My approach was that I built a full service that did this including being able to plug it into SES/Send

I liked the article as I once had a similar requirement! My approach was that I built a full service that did this including being able to plug it into SES/Sendgrid for sending and ability to add custom props etc... But then my other startup succeeded so I mothballed it. If anyone's interested, reach out!