SendGrid offers the largest volume freemium deal out of email providers: 12k. I have also heard rumors that has the best email server reputation, ie. is least likely to be tagged as spam. Spotify, Uber and Booking.com use SendGrid, to mention a few high profile clients.
Unlike MailGun, SendGrid does not offer powerful incoming email routing and forwarding features. For receiving email they offer a webhook API, which is not nativley supported by Discourse.
Anyone here using SendGrid and whats your setup? Could I use SendGrid for outbound and Mailgun for inbound?