Send Magic Link 500 - Ghost Mail Error - Ghost unable to send emails

So after updating to the 5.10 version of ghost to get some native comment functionality, my email sending capacity broke down.

I started getting 500 from the /send-magic-link HTTPS call.

But thanks to this thread I managed to sort it out again.

Here's the latest config.production.json that worked for me.

 "mail": {
    "from": "<EMAIL>",
    "transport": "SMTP",
    "options": {
      "service": "Mailgun",
      "host": "smtp.mailgun.org",
      "port": 465,
      "secure": true,
      "auth": {
        "user": "<USER>",
        "pass": "<PASS>"
      }
    }
  },
  "tls": {
    "rejectUnauthorized": false
  },

Thanks to this dude here for the solution: https://forum.ghost.org/t/ghost-unable-to-send-emails/9934/33