n8n: summarize incoming emails into Slack

Trigger on new email → SeaLink chat → post summary to Slack channel. No code, 10 minutes to ship.

GPT-4o mini Claude Haiku 4.5· 5 min read

Workflow

Gmail Trigger → HTTP Request (SeaLink) → Slack message. The HTTP node sends the email body to SeaLink's chat completions endpoint and gets back a summary.

n8n HTTP Request node config

POST to https://api.sealink.asia/v1/chat/completions with Authorization header. Body uses OpenAI-compatible JSON.

Body

{
  "model": "gpt-4o-mini",
  "messages": [
    {
      "role": "system",
      "content": "Summarize this email in 2 sentences. Reply in the same language as the email."
    },
    {
      "role": "user",
      "content": "{{$json[\"body\"]}}"
    }
  ],
  "max_tokens": 120
}

Send to Slack

Take {{$json.choices[0].message.content}} from the HTTP node response and pipe it into a Slack 'Post Message' node. Done.

Cost ballpark

100 emails / day × 30 days × ~500 tokens on gpt-4o-mini ≈ $0.45 / month. With SeaLink markup ≈ $0.47 / month.

Next steps