Earlier quoted context omitted.
So is the alternative/your expectation that they send each developer a custom email? If Twilio was to do that, that doesn't sound practical, scalable or smart.
The alternative would be to not include "RE:" in the subject, which makes it looks like a reply to an earlier thread. The subject is subject enough already. Don't manipulate it with a "RE:" to imply something more. That said, I've been working with Twilio on and off for 2 years and have never received an email like this from them.
Sorry about that, it's an easy fix to remove the RE: