My Mailgun account was first temporarily disabled. I contacted the support team and they asked me my purpose of creating it. I told them it’s for discourse forum…then I got the following response from them:
“ Hello ,
Thank you for contacting Sinch Mailgun Support.
After reviewing your account details and activity, we’ve decided to permanently disable your Mailgun account. Unfortunately, we are unable to fully disclose specific reasons behind this action in order to protect our customers, internal processes, and compliance systems . Our Terms of Service or Acceptable Use Policyare available on our website with more information.
If you’re setting up a new server it’s possible it’s been given an IP address that’s on a spam blacklist due to spamming in the past. They will block you because they suspect that spamming will continue, despite the address being owned by a different person. Or there could be a bunch of other reasons why they might not like you or your site.
You could try Mailjet - https://www.mailjet.com/ They work OK from Discourse for me, although depending on your email volumes you might find other providers who are cheaper.