Update: No further response from Mailgun, either via the original support ticket or from emailing directly. I switched our transactional emails to our own SMTP, but newsletter sending is dead.
I recognize the huge task it would be to support other bulk sending options, and I understand John’s reasoning on that. Unfortunately, for an increasing number of us, the issue with Mailgun is not that we don’t like them or their pricing, but that we’re being blocked (or for others, severely limited) from using their service and can’t go elsewhere. It’s a shame to have so much independence with Ghost and then be held hostage by someone else.
I hate the idea of going back to an external newsletter service after years with Ghost, but that seems to be the only way forward. Other advice welcome!