Task: Validate emails in a table using Mailcheck

n8n workflow JSON:
{"nodes":[{"name":"Airtable","type":"n8n-nodes-base.airtable","position":[470,200],"parameters":{"table":"Table 1","operation":"list","additionalOptions":{}},"credentials":{"airtableApi":""},"typeVersion":1},{"name":"Mailcheck","type":"n8n-nodes-base.mailcheck","position":[670,200],"parameters":{"email":"={{$json[\"fields\"][\"Email\"]}}"},"credentials":{"mailcheckApi":"Mailcheck API Credentials"},"typeVersion":1},{"name":"Set","type":"n8n-nodes-base.set","position":[870,200],"parameters":{"values":{"string":[{"name":"ID","value":"={{$node[\"Airtable\"].json[\"id\"]}}"}],"boolean":[{"name":"Valid","value":"={{$json[\"mxExists\"]}}"}]},"options":{},"keepOnlySet":true},"typeVersion":1},{"name":"Airtable1","type":"n8n-nodes-base.airtable","position":[1070,200],"parameters":{"id":"={{$json[\"ID\"]}}","table":"=Table 1","fields":["Valid"],"options":{},"operation":"update","application":"={{$node[\"Airtable\"].parameter[\"application\"]}}","updateAllFields":false},"credentials":{"airtableApi":"Airtable Credentials n8n"},"typeVersion":1}],"connections":{"Set":{"main":[[{"node":"Airtable1","type":"main","index":0}]]},"Airtable":{"main":[[{"node":"Mailcheck","type":"main","index":0}]]},"Mailcheck":{"main":[[{"node":"Set","type":"main","index":0}]]}}}