I have the same issue, and it’s incredibly frustrating.
To anyone who finds this thread via Google: I strongly recommend setting your batch limit to 9 recipients from the very beginning — otherwise, you might suddenly find your emails blocked without warning…
Following is Mailgun’s reply
After reviewing the account in detail, we have determined that the sending limitation will remain in effect temporarily due to the lack of sufficient sending history on the account.
To establish sufficient sending history with Mailgun and conclude the evaluation process, please conduct normal business operations with 3-5 days of consistent sending. We require your recipient email addresses to be collected organically and for those recipients to be double opt-in recipients. That means that they provided their email address directly to you themselves and have agreed to receive your correspondence. Once achieved, please update this ticket so that our team can re-evaluate the account and remove the sending limitation.
I understand that Mailgun may offer certain statistical advantages, but can anyone here actually explain what those are in practice?
Ghost relying solely on Mailgun for batch sending hurt its mission to “create the creator economy.”