MAIL_DRIVER=mailgun
MAIL_HOST=smtp.mailgun.org
MAILGUN_DOMAIN=sandbox48ec558**********************.mailgun.org
MAILGUN_SECRET=key-2***************************0

Client error: `POST
https://api.mailgun.net/v3/sandbox48ec558923d24853ac621e5582822b69.mailgun.org/messages.mime` resulted in a `400 BAD REQUEST` response:
{
"message": "Business Verification"
}