Late, but:
In addition to the DEFAULT_FROM_EMAIL
fix others have mentioned, and allowing less-secure apps to access the account, I had to navigate to https://accounts.google.com/DisplayUnlockCaptcha while signed in as the account in question to get Django to finally authenticate.
I went to that URL through a SSH tunnel to the web server to make sure the IP address was the same; I'm not totally sure if that's necessary but it can't hurt. You can do that like so: ssh -D 8080 -fN <username>@<host>
, then set your web browser to use localhost:8080
as a SOCKS proxy.