Improve AI Support Email Drafts with Gmail, Openai and Postgresql

The workflow JSON

Copy or download the full n8n JSON below. Paste it into a new n8n workflow, add your credentials, activate. Full import guide →

{
  "id": "OLnCF91fbGB6E9FGthJXi",
  "meta": {
    "templateCredsSetupCompleted": true
  },
  "name": "Feedback Loop",
  "tags": [],
  "nodes": [
    {
      "id": "5c7d4f79-b479-4c40-a092-0934e2e87169",
      "name": "\u23f0 Schedule - Every 3 Hours",
      "type": "n8n-nodes-base.scheduleTrigger",
      "position": [
        -2352,
        640
      ],
      "parameters": {
        "rule": {
          "interval": [
            {
              "field": "hours",
              "hoursInterval": 3
            }
          ]
        }
      },
      "typeVersion": 1.2
    },
    {
      "id": "fc095fb7-cdad-4f45-8384-d533101cbfe7",
      "name": "\ud83d\uddc4\ufe0f DB - Get Last Watermark",
      "type": "n8n-nodes-base.postgres",
      "position": [
        -2176,
        640
      ],
      "parameters": {
        "query": "SELECT last_processed_sent_at FROM feedback_run_log WHERE status = 'completed' ORDER BY run_completed_at DESC LIMIT 1;",
        "options": {},
        "operation": "executeQuery"
      },
      "credentials": {
        "postgres": {
          "name": "<your credential>"
        }
      },
      "typeVersion": 2.6
    },
    {
      "id": "43c7801f-2e51-4970-a498-c90de6cb3283",
      "name": "\u2699\ufe0f Set Watermark",
      "type": "n8n-nodes-base.code",
      "position": [
        -1952,
        640
      ],
      "parameters": {
        "jsCode": "const rows = $input.all();\nlet watermark;\n\nif (rows && rows.length > 0 && rows[0].json && rows[0].json.last_processed_sent_at) {\n  watermark = rows[0].json.last_processed_sent_at;\n} else {\n  // First run ever \u2014 go back 7 days\n  const d = new Date();\n  d.setDate(d.getDate() - 7);\n  watermark = d.toISOString();\n}\n\n// Unix timestamp for Gmail query\nconst unixTs = Math.floor(new Date(watermark).getTime() / 1000);\n\nreturn [{ json: { watermark, unixTs } }];"
      },
      "typeVersion": 2
    },
    {
      "id": "1fbc336f-2d9a-45ff-8448-11a585b2ed94",
      "name": "\ud83d\uddc4\ufe0f DB - Start Run Log",
      "type": "n8n-nodes-base.postgres",
      "position": [
        -1728,
        640
      ],
      "parameters": {
        "query": "INSERT INTO feedback_run_log (run_started_at, status) VALUES (NOW(), 'running') RETURNING id;",
        "options": {},
        "operation": "executeQuery"
      },
      "credentials": {
        "postgres": {
          "name": "<your credential>"
        }
      },
      "typeVersion": 2.6
    },
    {
      "id": "424f2c18-4a90-414d-85af-00f6ec627dfa",
      "name": "\u2699\ufe0f Carry Run Context",
      "type": "n8n-nodes-base.code",
      "position": [
        -1504,
        640
      ],
      "parameters": {
        "jsCode": "// Carry run_log_id forward alongside watermark\nconst runLogId = $input.first().json.id;\nconst watermark = $('\u2699\ufe0f Set Watermark').first().json.watermark;\nconst unixTs = $('\u2699\ufe0f Set Watermark').first().json.unixTs;\n\nreturn [{ json: { runLogId, watermark, unixTs } }];"
      },
      "typeVersion": 2
    },
    {
      "id": "08bf8015-b08f-42a2-9c58-4c5719fd0723",
      "name": "\ud83d\udce7 Gmail - Fetch Sent Emails",
      "type": "n8n-nodes-base.gmail",
      "position": [
        -1280,
        640
      ],
      "parameters": {
        "filters": {
          "q": "=in:sent after:{{ $json.unixTs }}"
        },
        "operation": "getAll",
        "returnAll": true
      },
      "credentials": {
        "gmailOAuth2": {
          "name": "<your credential>"
        }
      },
      "typeVersion": 2.2,
      "alwaysOutputData": true
    },
    {
      "id": "d21b20f9-d259-440f-a426-00b08189b29c",
      "name": "\ud83d\udd04 Loop - Sent Emails",
      "type": "n8n-nodes-base.splitInBatches",
      "position": [
        -1056,
        640
      ],
      "parameters": {
        "options": {
          "reset": false
        }
      },
      "typeVersion": 3
    },
    {
      "id": "8d74b94a-7d0f-4575-8de6-883e8e72ce2c",
      "name": "\ud83d\uddc4\ufe0f DB - Match Thread ID",
      "type": "n8n-nodes-base.postgres",
      "position": [
        16,
        912
      ],
      "parameters": {
        "query": "SELECT id, gmail_thread_id, gmail_message_id, original_email_body, classification, ai_draft_text, feedback_processed_at, was_approved_as_is FROM ai_drafts WHERE gmail_thread_id = '{{ $json.threadId }}' LIMIT 1;",
        "options": {},
        "operation": "executeQuery"
      },
      "credentials": {
        "postgres": {
          "name": "<your credential>"
        }
      },
      "typeVersion": 2.6,
      "alwaysOutputData": true
    },
    {
      "id": "4f9b5c5b-e2b2-48dc-9e22-794577d816da",
      "name": "\u2753 IF - Draft Match Found?",
      "type": "n8n-nodes-base.if",
      "position": [
        224,
        912
      ],
      "parameters": {
        "options": {},
        "conditions": {
          "options": {
            "version": 3,
            "leftValue": "",
            "caseSensitive": true,
            "typeValidation": "strict"
          },
          "combinator": "and",
          "conditions": [
            {
              "id": "b1+1234567890-+1234567890",
              "operator": {
                "type": "number",
                "operation": "exists",
                "singleValue": true
              },
              "leftValue": "={{ $json.id }}",
              "rightValue": ""
            }
          ]
        }
      },
      "typeVersion": 2.3
    },
    {
      "id": "fb1cd898-8b4c-4d4f-9945-7b03e1e489e2",
      "name": "\u2753 IF - Already Processed?",
      "type": "n8n-nodes-base.if",
      "position": [
        -784,
        288
      ],
      "parameters": {
        "options": {},
        "conditions": {
          "options": {
            "version": 3,
            "leftValue": "",
            "caseSensitive": true,
            "typeValidation": "strict"
          },
          "combinator": "and",
          "conditions": [
            {
              "id": "b1+1234567890-+1234567890",
              "operator": {
                "type": "string",
                "operation": "empty"
              },
              "leftValue": "={{ $json.feedback_processed_at }}",
              "rightValue": ""
            }
          ]
        }
      },
      "typeVersion": 2.3
    },
    {
      "id": "f982e930-4766-4015-b4e5-1f4882351e62",
      "name": "\ud83e\udd16 AI - Compare Draft vs Sent",
      "type": "@n8n/n8n-nodes-langchain.agent",
      "position": [
        -576,
        272
      ],
      "parameters": {
        "text": "=ORIGINAL CUSTOMER EMAIL:\n{{ $('\ud83d\udd04 Loop - Sent Emails').item.json.text || $('\ud83d\udd04 Loop - Sent Emails').item.json.body || '' }}\n\nAI DRAFT (what the system generated):\n{{ $('\ud83d\uddc4\ufe0f DB - Match Thread ID').item.json.ai_draft_text }}\n\nHUMAN SENT (what was actually sent to the customer):\n{{ $json.text || $json.body || '' }}\n\nCLASSIFICATION: {{ $('\ud83d\uddc4\ufe0f DB - Match Thread ID').item.json.classification }}\n\nAnalyze the difference between the AI draft and the human-sent email. Respond ONLY with this exact JSON, no markdown, no explanation:\n{\n  \"approved_as_is\": true or false,\n  \"edit_type\": \"none\" or \"minor_edits\" or \"major_rewrite\",\n  \"diff_summary\": \"Plain English description of what changed and why it likely changed. Be specific.\",\n  \"tone_shift\": \"more_formal\" or \"more_casual\" or \"same\" or \"n/a\",\n  \"info_added\": true or false,\n  \"info_removed\": true or false,\n  \"kb_update_needed\": true or false,\n  \"kb_update_reason\": \"Why the KB needs updating, or null if not needed\",\n  \"kb_category\": \"The category from the classification that should be updated, or null\",\n  \"kb_new_info\": \"The specific new information or correction to add to the KB, or null\"\n}",
        "options": {
          "maxIterations": 3
        },
        "promptType": "define"
      },
      "typeVersion": 3.1
    },
    {
      "id": "421e6376-4c88-45c8-b1ea-3127e51682fd",
      "name": "OpenAI Chat Model - Compare",
      "type": "@n8n/n8n-nodes-langchain.lmChatOpenAi",
      "position": [
        -320,
        144
      ],
      "parameters": {
        "model": {
          "__rl": true,
          "mode": "list",
          "value": "gpt-4o-mini",
          "cachedResultName": "gpt-4o-mini"
        },
        "options": {
          "maxTokens": 800,
          "temperature": 0,
          "presencePenalty": 0,
          "frequencyPenalty": 0
        },
        "builtInTools": {}
      },
      "credentials": {
        "openAiApi": {
          "name": "<your credential>"
        }
      },
      "typeVersion": 1.3
    },
    {
      "id": "6e4090dc-8610-45f7-af03-df16ba65a569",
      "name": "\u2699\ufe0f Parse AI Comparison",
      "type": "n8n-nodes-base.code",
      "position": [
        -224,
        272
      ],
      "parameters": {
        "jsCode": "const item = $input.first().json;\nconst rawOutput = item.output || '';\nconst cleaned = rawOutput\n  .replace(/```json/gi, '')\n  .replace(/```/g, '')\n  .trim();\n\nlet parsed;\ntry {\n  parsed = JSON.parse(cleaned);\n} catch(e) {\n  parsed = {\n    approved_as_is: false,\n    edit_type: 'parse_error',\n    diff_summary: 'Failed to parse AI comparison response',\n    tone_shift: 'n/a',\n    info_added: false,\n    info_removed: false,\n    kb_update_needed: false,\n    kb_update_reason: null,\n    kb_category: null,\n    kb_new_info: null\n  };\n}\n\n// Carry through the sent email body and thread context\n// The loop item flows into DB - Match Thread ID as input\n// so reference the sent email body from the IF node before it\nconst sentBody = $('\u2699\ufe0f Parse Full Message Body').item.json.sentBody || '';\nconst draftId = $('\ud83d\uddc4\ufe0f DB - Match Thread ID').item.json.id;\nconst originalBody = $('\ud83d\uddc4\ufe0f DB - Match Thread ID').item.json.original_email_body;\nconst classification = $('\ud83d\uddc4\ufe0f DB - Match Thread ID').item.json.classification;\nconst aiDraftText = $('\ud83d\uddc4\ufe0f DB - Match Thread ID').item.json.ai_draft_text;\n\nreturn [{\n  json: {\n    ...parsed,\n    sentBody,\n    draftId,\n    originalBody,\n    classification,\n    aiDraftText\n  }\n}];"
      },
      "typeVersion": 2
    },
    {
      "id": "a287218e-4a5e-4dab-99ea-0e33da8b1873",
      "name": "\u2753 IF - Approved As-Is?",
      "type": "n8n-nodes-base.if",
      "position": [
        0,
        272
      ],
      "parameters": {
        "options": {},
        "conditions": {
          "options": {
            "version": 3,
            "leftValue": "",
            "caseSensitive": true,
            "typeValidation": "strict"
          },
          "combinator": "and",
          "conditions": [
            {
              "id": "b1+1234567890-+1234567890",
              "operator": {
                "type": "boolean",
                "operation": "equals"
              },
              "leftValue": "={{ $json.approved_as_is }}",
              "rightValue": true
            }
          ]
        }
      },
      "typeVersion": 2.3
    },
    {
      "id": "0155b7f2-bcd4-4819-a00e-e7d07b06485a",
      "name": "\ud83d\uddc4\ufe0f DB - Mark Approved As-Is",
      "type": "n8n-nodes-base.postgres",
      "position": [
        224,
        256
      ],
      "parameters": {
        "query": "UPDATE ai_drafts SET was_approved_as_is = TRUE, feedback_processed_at = NOW() WHERE id = {{ $json.draftId }};",
        "options": {},
        "operation": "executeQuery"
      },
      "credentials": {
        "postgres": {
          "name": "<your credential>"
        }
      },
      "typeVersion": 2.6
    },
    {
      "id": "c8362985-ba49-4170-a9ae-bb10647966fd",
      "name": "\ud83d\udd22 Generate Embedding - Human Sent",
      "type": "n8n-nodes-base.httpRequest",
      "position": [
        64,
        528
      ],
      "parameters": {
        "url": "https://api.openai.com/v1/embeddings",
        "method": "POST",
        "options": {},
        "sendBody": true,
        "authentication": "predefinedCredentialType",
        "bodyParameters": {
          "parameters": [
            {
              "name": "model",
              "value": "text-embedding-3-small"
            },
            {
              "name": "input",
              "value": "={{ $json.sentBody }}"
            }
          ]
        },
        "nodeCredentialType": "openAiApi"
      },
      "credentials": {
        "openAiApi": {
          "name": "<your credential>"
        }
      },
      "typeVersion": 4.4
    },
    {
      "id": "37c6deac-6deb-4b41-9270-3e817766f76b",
      "name": "\u2699\ufe0f Extract Embedding",
      "type": "n8n-nodes-base.code",
      "position": [
        288,
        528
      ],
      "parameters": {
        "jsCode": "const item = $input.first().json;\nconst embeddingArray = item.data[0].embedding;\nconst vectorString = '[' + embeddingArray.join(',') + ']';\n\nconst prev = $('\u2699\ufe0f Parse AI Comparison').first().json;\n\nreturn [{\n  json: {\n    embedding: vectorString,\n    sentBody: prev.sentBody,\n    draftId: prev.draftId,\n    originalBody: prev.originalBody,\n    classification: prev.classification,\n    aiDraftText: prev.aiDraftText,\n    diff_summary: prev.diff_summary,\n    kb_update_needed: prev.kb_update_needed,\n    kb_update_reason: prev.kb_update_reason,\n    kb_category: prev.kb_category,\n    kb_new_info: prev.kb_new_info\n  }\n}];"
      },
      "typeVersion": 2
    },
    {
      "id": "2e318078-fee1-4729-a59b-1816a7db3188",
      "name": "\ud83d\uddc4\ufe0f DB - Save Correction",
      "type": "n8n-nodes-base.postgres",
      "position": [
        512,
        528
      ],
      "parameters": {
        "query": "INSERT INTO corrections (\n  ai_draft_id,\n  original_email_body,\n  classification,\n  ai_draft_text,\n  human_sent_text,\n  diff_summary,\n  embedding,\n  source,\n  kb_updated\n) VALUES (\n  {{ $json.draftId }},\n  $1,\n  $2,\n  $3,\n  $4,\n  $5,\n  $6::vector,\n  'feedback_loop',\n  FALSE\n) RETURNING id;",
        "options": {
          "queryReplacement": "={{ [$json.originalBody, $json.classification, $json.aiDraftText, $json.sentBody, $json.diff_summary, $json.embedding] }}"
        },
        "operation": "executeQuery"
      },
      "credentials": {
        "postgres": {
          "name": "<your credential>"
        }
      },
      "typeVersion": 2.6
    },
    {
      "id": "33d6c979-c122-4efc-9e54-21ece23e788e",
      "name": "\ud83d\uddc4\ufe0f DB - Mark Draft Processed",
      "type": "n8n-nodes-base.postgres",
      "position": [
        736,
        528
      ],
      "parameters": {
        "query": "UPDATE ai_drafts SET feedback_processed_at = NOW() WHERE id = {{ $('\u2699\ufe0f Extract Embedding').item.json.draftId }};",
        "options": {},
        "operation": "executeQuery"
      },
      "credentials": {
        "postgres": {
          "name": "<your credential>"
        }
      },
      "typeVersion": 2.6
    },
    {
      "id": "afffe5e1-9615-4342-939a-4202a3dc163f",
      "name": "\u2753 IF - KB Update Needed?",
      "type": "n8n-nodes-base.if",
      "position": [
        944,
        528
      ],
      "parameters": {
        "options": {},
        "conditions": {
          "options": {
            "version": 3,
            "leftValue": "",
            "caseSensitive": true,
            "typeValidation": "strict"
          },
          "combinator": "and",
          "conditions": [
            {
              "id": "b1+1234567890-+1234567890",
              "operator": {
                "type": "boolean",
                "operation": "equals"
              },
              "leftValue": "={{ $('\u2699\ufe0f Parse AI Comparison').item.json.kb_update_needed }}",
              "rightValue": true
            }
          ]
        }
      },
      "typeVersion": 2.3
    },
    {
      "id": "ac859ee7-262e-4f49-897c-0b8ee107248e",
      "name": "\ud83d\uddc4\ufe0f DB - Fetch KB Entry to Update",
      "type": "n8n-nodes-base.postgres",
      "position": [
        1168,
        512
      ],
      "parameters": {
        "query": "SELECT id, category, question, answer FROM kb_data WHERE category = $1 ORDER BY updated_at DESC LIMIT 1;",
        "options": {
          "queryReplacement": "={{ [$('\u2699\ufe0f Parse AI Comparison').item.json.kb_category] }}"
        },
        "operation": "executeQuery"
      },
      "credentials": {
        "postgres": {
          "name": "<your credential>"
        }
      },
      "typeVersion": 2.6
    },
    {
      "id": "87e04269-1321-4be0-9466-eb806f54b907",
      "name": "\ud83e\udd16 AI - Rewrite KB Answer",
      "type": "@n8n/n8n-nodes-langchain.openAi",
      "position": [
        1360,
        512
      ],
      "parameters": {
        "modelId": {
          "__rl": true,
          "mode": "list",
          "value": "gpt-4o-mini"
        },
        "options": {
          "maxTokens": 500,
          "temperature": 0.2
        },
        "simplify": false,
        "responses": {
          "values": [
            {
              "role": "system",
              "content": "You are updating a knowledge base entry for a customer support system at InCred Money, a platform for trading unlisted pre-IPO shares. Rewrite the KB answer to incorporate new information while preserving all existing correct content. Respond with ONLY the new answer text. No preamble, no explanation, no markdown."
            },
            {
              "content": "=EXISTING KB ENTRY:\nCategory: {{ $json.category }}\nQuestion: {{ $json.question }}\nCurrent Answer: {{ $json.answer }}\n\nNEW INFORMATION TO INCORPORATE:\n{{ $('\u2699\ufe0f Parse AI Comparison').item.json.kb_new_info }}\n\nREASON FOR UPDATE:\n{{ $('\u2699\ufe0f Parse AI Comparison').item.json.kb_update_reason }}\n\nRewrite the answer incorporating the new information."
            }
          ]
        },
        "builtInTools": {}
      },
      "credentials": {
        "openAiApi": {
          "name": "<your credential>"
        }
      },
      "typeVersion": 2.1
    },
    {
      "id": "d3eb84c2-227a-466f-80f2-57dbf087e1cf",
      "name": "\ud83d\uddc4\ufe0f DB - Update KB Entry",
      "type": "n8n-nodes-base.postgres",
      "position": [
        1696,
        512
      ],
      "parameters": {
        "query": "UPDATE kb_data SET previous_answer = answer, answer = $1, updated_by = 'ai_feedback_loop', updated_at = NOW() WHERE id = {{ $('\ud83d\uddc4\ufe0f DB - Fetch KB Entry to Update').item.json.id }};",
        "options": {
          "queryReplacement": "={{ [$json.message?.content?.[0]?.text || $json.output || ''] }}"
        },
        "operation": "executeQuery"
      },
      "credentials": {
        "postgres": {
          "name": "<your credential>"
        }
      },
      "typeVersion": 2.6
    },
    {
      "id": "ca26d98e-853e-4d13-9dc0-4b8cfd229624",
      "name": "\ud83d\uddc4\ufe0f DB - Mark KB Updated",
      "type": "n8n-nodes-base.postgres",
      "position": [
        1888,
        624
      ],
      "parameters": {
        "query": "UPDATE corrections SET kb_updated = TRUE WHERE ai_draft_id = {{ $('\u2699\ufe0f Extract Embedding').item.json.draftId }} AND source = 'feedback_loop' ORDER BY created_at DESC LIMIT 1;",
        "options": {},
        "operation": "executeQuery"
      },
      "credentials": {
        "postgres": {
          "name": "<your credential>"
        }
      },
      "typeVersion": 2.6
    },
    {
      "id": "a3437287-ee6e-46bb-b8a4-f5f2bc4795c3",
      "name": "\ud83d\uddc4\ufe0f DB - Complete Run Log",
      "type": "n8n-nodes-base.postgres",
      "position": [
        -784,
        560
      ],
      "parameters": {
        "query": "UPDATE feedback_run_log SET run_completed_at = NOW(), last_processed_sent_at = NOW(), status = 'completed' WHERE id = {{ $('\ud83d\uddc4\ufe0f DB - Start Run Log').first().json.id }};",
        "options": {},
        "operation": "executeQuery"
      },
      "credentials": {
        "postgres": {
          "name": "<your credential>"
        }
      },
      "typeVersion": 2.6
    },
    {
      "id": "554c5627-7ed7-4234-864b-498f40054607",
      "name": "\ud83d\udce7 Gmail - Fetch Full Message",
      "type": "n8n-nodes-base.httpRequest",
      "position": [
        -384,
        912
      ],
      "parameters": {
        "url": "=https://www.googleapis.com/gmail/v1/users/me/messages/{{ $json.id }}?format=full",
        "options": {},
        "authentication": "predefinedCredentialType",
        "nodeCredentialType": "gmailOAuth2"
      },
      "credentials": {
        "gmailOAuth2": {
          "name": "<your credential>"
        }
      },
      "typeVersion": 4.4
    },
    {
      "id": "5bd58454-bc56-4850-9f90-e8c53cbeaeeb",
      "name": "\u2699\ufe0f Parse Full Message Body",
      "type": "n8n-nodes-base.code",
      "position": [
        -192,
        912
      ],
      "parameters": {
        "jsCode": "const item = $input.first().json;\n\nfunction decodeBase64url(str) {\n  if (!str) return '';\n  return Buffer.from(str.replace(/-/g, '+').replace(/_/g, '/'), 'base64').toString('utf-8');\n}\n\nfunction extractTextPlain(payload) {\n  if (!payload) return '';\n\n  // CASE 1: Direct body.data on payload (text/plain, no parts) \u2190 this email's structure\n  if (payload.mimeType === 'text/plain' && payload.body?.data) {\n    return decodeBase64url(payload.body.data);\n  }\n\n  // CASE 2: Nested parts (multipart/alternative, multipart/mixed etc.)\n  if (payload.parts && payload.parts.length > 0) {\n    for (const part of payload.parts) {\n      const result = extractTextPlain(part); // recursive\n      if (result) return result;\n    }\n  }\n\n  return '';\n}\n\nfunction stripQuotedReply(text) {\n  const lines = text.split('\\n');\n  const replyLines = [];\n  for (const line of lines) {\n    if (line.startsWith('>')) break;\n    if (/^On .+wrote:$/i.test(line.trim())) break;\n    if (line.includes('---------- Forwarded message')) break;\n    replyLines.push(line);\n  }\n  return replyLines.join('\\n').replace(/\\r/g, '').replace(/\\n{3,}/g, '\\n\\n').trim();\n}\n\nlet sentBody = extractTextPlain(item.payload);\nsentBody = stripQuotedReply(sentBody);\n\nif (!sentBody) sentBody = item.snippet || '';\n\nconst loopItem = $('\ud83d\udd04 Loop - Sent Emails').item.json;\n\nreturn [{\n  json: {\n    ...loopItem,\n    sentBody,\n    threadId: item.threadId,\n    messageId: item.id\n  }\n}];"
      },
      "typeVersion": 2
    },
    {
      "id": "b47598a7-6bbd-4cb8-a30f-d6e3415949d6",
      "name": "Sticky Note",
      "type": "n8n-nodes-base.stickyNote",
      "position": [
        -3168,
        32
      ],
      "parameters": {
        "width": 656,
        "height": 848,
        "content": "## Self-learning feedback loop for AI email drafts\n\nThis workflow runs every 3 hours and checks which AI-generated \nemail drafts have been reviewed and sent by the support team. \nIt compares the AI draft against what was actually sent, learns \nfrom the differences, and stores human-approved responses as \ntraining examples for future drafts.\n\nOver time, the main email workflow surfaces increasingly relevant \npast responses via vector similarity search \u2014 no fine-tuning needed.\n\n## How it works\n\n1. Fetches watermark from last completed run \u2014 only new sent \n   emails are processed each time\n2. Gmail Sent folder is fetched since the watermark timestamp\n3. Each sent email is matched to an AI draft via thread ID\n4. Already-processed drafts are skipped automatically\n5. AI compares the draft vs actual sent email and classifies \n   the type of edit made\n6. If sent unchanged \u2014 marked approved-as-is, loop continues\n7. If edited \u2014 embedding generated, correction saved to DB \n   for future similarity search\n8. If edit reveals missing KB info \u2014 KB entry auto-updated\n\n## Setup steps\n\n1. Connect Gmail OAuth2 to the Gmail Fetch Sent node\n2. Connect PostgreSQL credential to all DB nodes\n3. Connect OpenAI API to the Chat Model and embedding nodes\n4. Run the DB migration SQL to add feedback columns and \n   create the feedback_run_log table\n5. Ensure Workflow 1 (email draft automation) is already \n   active and generating drafts\n6. Activate \u2014 runs automatically every 3 hours"
      },
      "typeVersion": 1
    },
    {
      "id": "2ca9131b-ae98-41be-ac18-2e94c02d6155",
      "name": "Sticky Note1",
      "type": "n8n-nodes-base.stickyNote",
      "position": [
        -2496,
        480
      ],
      "parameters": {
        "color": 7,
        "width": 1360,
        "height": 400,
        "content": "## Schedule & Fetch Emails\n\nRuns every 3 hours. Fetches last_processed_sent_at from the \nmost recent completed run as a watermark \u2014 so only new sent \nemails are fetched each time. First-ever run defaults to 7 days ago."
      },
      "typeVersion": 1
    },
    {
      "id": "4e9841ac-1ea9-4fae-a97e-8cca892f5771",
      "name": "Sticky Note2",
      "type": "n8n-nodes-base.stickyNote",
      "position": [
        -864,
        832
      ],
      "parameters": {
        "color": 7,
        "width": 1280,
        "height": 336,
        "content": "## Loop & thread matching\n\nProcesses one sent email at a time. Full message body is fetched \nvia Gmail API separately \u2014 the Sent folder list only returns a \nsnippet. Each email is matched to an AI draft by thread ID. \nNo match or already processed = skip."
      },
      "typeVersion": 1
    },
    {
      "id": "2aebc058-79a7-4de6-9fd7-16593f15919a",
      "name": "Sticky Note3",
      "type": "n8n-nodes-base.stickyNote",
      "position": [
        -864,
        -16
      ],
      "parameters": {
        "color": 7,
        "width": 1280,
        "height": 480,
        "content": "## AI comparison & branching\n\nGPT-4o-mini compares the AI draft vs human-sent email and returns \nedit type, a plain-English diff summary, and whether a KB update \nis needed.\n\nApproved as-is \u2192 mark draft, continue loop\nEdited/rewritten \u2192 generate embedding, save to corrections table"
      },
      "typeVersion": 1
    },
    {
      "id": "d41b364f-5010-4a01-95dd-564bf474b2e5",
      "name": "Sticky Note4",
      "type": "n8n-nodes-base.stickyNote",
      "position": [
        -464,
        480
      ],
      "parameters": {
        "color": 7,
        "width": 2528,
        "height": 336,
        "content": "## Corrections & KB update\n\nHuman-edited pairs are embedded and saved to the corrections \ntable \u2014 this is what Workflow 1 queries for similarity search \nwhen drafting future replies.\n\nIf the edit contained new information, the matching KB entry \nis rewritten by AI. Previous answer is preserved for audit."
      },
      "typeVersion": 1
    }
  ],
  "active": false,
  "settings": {
    "binaryMode": "separate",
    "availableInMCP": false,
    "executionOrder": "v1"
  },
  "versionId": "09b7acc8-474c-4f82-b57c-95474987c1c1",
  "connections": {
    "\u2699\ufe0f Set Watermark": {
      "main": [
        [
          {
            "node": "\ud83d\uddc4\ufe0f DB - Start Run Log",
            "type": "main",
            "index": 0
          }
        ]
      ]
    },
    "\ud83d\udd04 Loop - Sent Emails": {
      "main": [
        [
          {
            "node": "\ud83d\uddc4\ufe0f DB - Complete Run Log",
            "type": "main",
            "index": 0
          }
        ],
        [
          {
            "node": "\ud83d\udce7 Gmail - Fetch Full Message",
            "type": "main",
            "index": 0
          }
        ]
      ]
    },
    "\u2699\ufe0f Carry Run Context": {
      "main": [
        [
          {
            "node": "\ud83d\udce7 Gmail - Fetch Sent Emails",
            "type": "main",
            "index": 0
          }
        ]
      ]
    },
    "\u2699\ufe0f Extract Embedding": {
      "main": [
        [
          {
            "node": "\ud83d\uddc4\ufe0f DB - Save Correction",
            "type": "main",
            "index": 0
          }
        ]
      ]
    },
    "\u2753 IF - Approved As-Is?": {
      "main": [
        [
          {
            "node": "\ud83d\uddc4\ufe0f DB - Mark Approved As-Is",
            "type": "main",
            "index": 0
          }
        ],
        [
          {
            "node": "\ud83d\udd22 Generate Embedding - Human Sent",
            "type": "main",
            "index": 0
          }
        ]
      ]
    },
    "\u2699\ufe0f Parse AI Comparison": {
      "main": [
        [
          {
            "node": "\u2753 IF - Approved As-Is?",
            "type": "main",
            "index": 0
          }
        ]
      ]
    },
    "\u2753 IF - KB Update Needed?": {
      "main": [
        [
          {
            "node": "\ud83d\uddc4\ufe0f DB - Fetch KB Entry to Update",
            "type": "main",
            "index": 0
          }
        ],
        [
          {
            "node": "\ud83d\udd04 Loop - Sent Emails",
            "type": "main",
            "index": 0
          }
        ]
      ]
    },
    "\ud83d\uddc4\ufe0f DB - Start Run Log": {
      "main": [
        [
          {
            "node": "\u2699\ufe0f Carry Run Context",
            "type": "main",
            "index": 0
          }
        ]
      ]
    },
    "OpenAI Chat Model - Compare": {
      "ai_languageModel": [
        [
          {
            "node": "\ud83e\udd16 AI - Compare Draft vs Sent",
            "type": "ai_languageModel",
            "index": 0
          }
        ]
      ]
    },
    "\u2753 IF - Already Processed?": {
      "main": [
        [
          {
            "node": "\ud83e\udd16 AI - Compare Draft vs Sent",
            "type": "main",
            "index": 0
          }
        ],
        [
          {
            "node": "\ud83d\udd04 Loop - Sent Emails",
            "type": "main",
            "index": 0
          }
        ]
      ]
    },
    "\u2753 IF - Draft Match Found?": {
      "main": [
        [
          {
            "node": "\u2753 IF - Already Processed?",
            "type": "main",
            "index": 0
          }
        ],
        [
          {
            "node": "\ud83d\udd04 Loop - Sent Emails",
            "type": "main",
            "index": 0
          }
        ]
      ]
    },
    "\ud83e\udd16 AI - Rewrite KB Answer": {
      "main": [
        [
          {
            "node": "\ud83d\uddc4\ufe0f DB - Update KB Entry",
            "type": "main",
            "index": 0
          }
        ]
      ]
    },
    "\u23f0 Schedule - Every 3 Hours": {
      "main": [
        [
          {
            "node": "\ud83d\uddc4\ufe0f DB - Get Last Watermark",
            "type": "main",
            "index": 0
          }
        ]
      ]
    },
    "\ud83d\uddc4\ufe0f DB - Mark KB Updated": {
      "main": [
        [
          {
            "node": "\ud83d\udd04 Loop - Sent Emails",
            "type": "main",
            "index": 0
          }
        ]
      ]
    },
    "\ud83d\uddc4\ufe0f DB - Match Thread ID": {
      "main": [
        [
          {
            "node": "\u2753 IF - Draft Match Found?",
            "type": "main",
            "index": 0
          }
        ]
      ]
    },
    "\ud83d\uddc4\ufe0f DB - Save Correction": {
      "main": [
        [
          {
            "node": "\ud83d\uddc4\ufe0f DB - Mark Draft Processed",
            "type": "main",
            "index": 0
          }
        ]
      ]
    },
    "\ud83d\uddc4\ufe0f DB - Update KB Entry": {
      "main": [
        [
          {
            "node": "\ud83d\uddc4\ufe0f DB - Mark KB Updated",
            "type": "main",
            "index": 0
          }
        ]
      ]
    },
    "\u2699\ufe0f Parse Full Message Body": {
      "main": [
        [
          {
            "node": "\ud83d\uddc4\ufe0f DB - Match Thread ID",
            "type": "main",
            "index": 0
          }
        ]
      ]
    },
    "\ud83d\udce7 Gmail - Fetch Sent Emails": {
      "main": [
        [
          {
            "node": "\ud83d\udd04 Loop - Sent Emails",
            "type": "main",
            "index": 0
          }
        ]
      ]
    },
    "\ud83d\udce7 Gmail - Fetch Full Message": {
      "main": [
        [
          {
            "node": "\u2699\ufe0f Parse Full Message Body",
            "type": "main",
            "index": 0
          }
        ]
      ]
    },
    "\ud83d\uddc4\ufe0f DB - Get Last Watermark": {
      "main": [
        [
          {
            "node": "\u2699\ufe0f Set Watermark",
            "type": "main",
            "index": 0
          }
        ]
      ]
    },
    "\ud83e\udd16 AI - Compare Draft vs Sent": {
      "main": [
        [
          {
            "node": "\u2699\ufe0f Parse AI Comparison",
            "type": "main",
            "index": 0
          }
        ]
      ]
    },
    "\ud83d\uddc4\ufe0f DB - Mark Approved As-Is": {
      "main": [
        [
          {
            "node": "\ud83d\udd04 Loop - Sent Emails",
            "type": "main",
            "index": 0
          }
        ]
      ]
    },
    "\ud83d\uddc4\ufe0f DB - Mark Draft Processed": {
      "main": [
        [
          {
            "node": "\u2753 IF - KB Update Needed?",
            "type": "main",
            "index": 0
          }
        ]
      ]
    },
    "\ud83d\udd22 Generate Embedding - Human Sent": {
      "main": [
        [
          {
            "node": "\u2699\ufe0f Extract Embedding",
            "type": "main",
            "index": 0
          }
        ]
      ]
    },
    "\ud83d\uddc4\ufe0f DB - Fetch KB Entry to Update": {
      "main": [
        [
          {
            "node": "\ud83e\udd16 AI - Rewrite KB Answer",
            "type": "main",
            "index": 0
          }
        ]
      ]
    }
  }
}

Credentials you'll need

Each integration node will prompt for credentials when you import. We strip credential IDs before publishing — you'll add your own.

• gmailOAuth2
• openAiApi
• postgres

About this workflow

Automatically compare AI-generated email drafts against what your support team actually sent, learn from the differences, and improve future drafts over time — without any model fine-tuning.

Source: https://n8n.io/workflows/13978/ — original creator credit. Request a take-down →

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