Hello! I tried to configure Mailgun using AdminFE and config.exs, but it returns this on verification letter:
akkoma-server-1 | 20:17:14.831 [warning] Description: 'Authenticity is not established by certificate path validation'
akkoma-server-1 | Reason: 'Option {verify, verify_peer} and cacertfile/cacerts is missing'
Could it be possible, that your server is missing a package containing ca certificates? What operating system are you using? If you try to access mailgun via curl on your server, does it work?
Well, I asked more knowledgeable friends that do this for a job and they said change that, and it worked.
Unsure if related to your mail setup, but sharing just in case.