I just want to say that things like this have instantly added to the respect I have for Mailgun as a company. I know that's unrelated to the OP, and I may get down voted for this, but I feel as though for as much as a complain about an absence of good customer service - I would be remiss not to acknowledge it when I see it.
I have had a few questions/issues during development and the live-support was simply brilliant. Meanwhile I switched 2 of my Rails apps from Sendgrid to MailGun.
Thank you.