Improve deliverability of email

[kimberscott]

TL;DR

Emails, including compensation emails, are often getting filtered as spam.

Narrative

As a researcher, I want to be confident I'm actually reaching participants when I use the Lookit interface to send messages. This affects our reputation as well. As a participant, I want to receive email from researchers, particularly when that email contains compensation for a study we participated in.

To consider:

• Figure out how often this is happening (may need to talk with researchers who get direct complaints)
• Figure out why emails are getting flagged as spam (is it our language? headers? from address vs. reply_to?)
• Can we use an MIT SMTP server instead?
• Would authenticating a domain via SendGrid help if sticking with SendGrid?

[becky-gilbert]

Closing this issue as it is superseded by #1340