I have a production Django application that uses SendGrid to send emails to our clients. Most of our clients haven't had any issues until recently. We are now dealing with a few larger companies who have blacklisted .sendgrid.net, and are suggesting we use an alternate method of sending emails. I have authenticated the domain so that each email is digitally signed by our domain, but this still isn't good enough to get past the spam filters. Does anyone have any alternatives? Or I am thinking maybe I will just use the python email library to send the emails one by one. Any help is appreciated! Thanks!