In your config.production.json add following entry

	"mail": {
		"from": "info@transang.me",
		"transport": "SMTP",
		"options": {
			"port": 587,
			"host": "smtp.sendgrid.net",
			"secureConnection": false,
			"auth": {
				"user": "apikey",
				"pass": "your sendgrid API key in plain text"
			}
		}
	}

Note that secureConnection must be false or ignored (its false by default)