For more information about why your email was unsuccessful, please click the ⚠️(red triangle) icon to view more details:

Error list:

Log in to Mailgun - https://login.mailgun.com/login/   

1. Expand Sending tab

2. Click the last menu item Domain Settings

3. Make sure you select the correct domain/subdomain for the location on top

4. Click DNS records on the top middle

5. Click Verify DNS settings and see if all 5 DNS records have a green checkmark?

Sometimes it might show if they have all green checkmarks but it might not be the case, you will need to click the Verify DNS Settings button again to refresh the record: 

Domain is not allowed to send: Account Terminated

Agency will need to reach out to Mailgun support to see why it got terminated

Too old

It is one of Mailgun's internal errors that you can clear in the agency settings. But to find out the reason why you are getting that error, you will need to reach out to Mailgun support to check further.

Send verification error

https://help.mailgun.com/hc/en-us/articles/360011804533-Sender-Verification-Error