Add mail settings to env file

.env.sample

@@ -5,4 +5,12 @@ DOMAIN=ghost.example.com
 ## Domain aliases
 #EXTRA_DOMAINS=', `www.ghost.example.com`'
 LETS_ENCRYPT_ENV=production
-PT_ENV=production
+
+## Mail settings
+#MAIL_TRANSPORT=smtp
+#MAIL_FROM=admin@example.com
+#MAIL_OPTIONS_HOST=mail.example.com
+#MAIL_OPTIONS_PORT=587
+#MAIL_OPTIONS_SECURE=false
+#MAIL_OPTIONS_AUTH_USER=smtpuser@example.com
+#MAIL_OPTIONS_AUTH_PASS=XXXX