1. mailkube
mailkube.com$27 vs $75 at 100k emails
mailkube is cheaper than Mailgun at every volume shown, e.g. $7 vs $15 at 10,000 emails/month, $27 vs $75 at 100,000, and $489 vs $877 at 1,000,000 (savings of $48 to $388 from 100,000 emails/month with dedicated IPs matched).