I want to use GmailApp from Google Apps Script to send marketing follow-up emails from gmail. But of course everything from Google is fucked up, and GmailApp won't let me set the "to" in a reply and sets the "sender" to whoever runs the script. In other words, I have no control over the email. So instead I want to use UrlFetchApp to call some REST API to send emails so that I can control the email. Does anyone know of such a service that is simple to use? I presume not, since all modern software is shit, and so I will have to write my own, as usual.