They are actually one of the few services that u can use for programmatically receiving emails. When it works, it just works - but unfortunately the spam thing bit us as well.
Fortunately we were able to get it resolved quickly
They provide MX forwarding for delivery, but we use them because it saves us from having to buy a per user email account with gsuite or outlook. It's a little bit of a hassle/hack, but it works well enough in practice. I use a free gmail account that receives forwarded emails from Mailgun, and I can respond via mailgun smtp within gmail.
Fortunately we were able to get it resolved quickly