Unfortunately, Mailgun is throttling the domain due to large rates of mail. All we can do is wait the ban out, I'm afraid.
Looks like you need a new domain provider; this is a show stopper.
I would agree, but I make liberal use of the free limits so I can't complain much. I don't really want to spend too much money running Spamnesty.
Are you able to easily detect whether your account is currently blocked and add some warning to the front page? Would make it easier than just spamming sp@mnesty.com until the mails don't bounce anymore...
I don't think Mailgun expose that in any API, I'm afraid. Good idea, though, I'll see if there's something available.
Same... I think they need a service status page
Same here, in Gmail.
Same here, Office365.
Same here, also Gmail. Maybe it's overloaded right now?