The initial limits Mailgun places on the Flex plan for self-hosting Ghost users are just dealbreakers. As I was told today, that you are limited to 9-send batches, and no more than 100 sends an hour, makes it basically useless for anyone coming to Ghost with significant subscribers from another service, whether Wordpress, Substack, or whatever. You can’t be left in limbo wondering when you’ll ever be fully ungated and able to send to all your subscribers.
I know this has been asked and answered repeatedly, but Ghost really needs to support more than one bulk email service. Being held hostage by Mailgun is good for no-one.