Apply suggestion from @notamitgamer

domains/send.eunsunglee.json

@@ -1,6 +1,6 @@
 {
   "owner": { "username": "eunsunglee0524" },
-  "record": {
+  "records": {
     "MX": [{ "priority": 10, "value": "feedback-smtp.ap-northeast-1.amazonses.com" }],
     "TXT": ["v=spf1 include:amazonses.com ~all"]
   }