Warm up Gmail inboxes with OpenAI GPT-4o-mini and Data Tables

Automatically warm up multiple Gmail inboxes with human-like email conversations, smart scheduling, and auto read/reply, powered by n8n Data Tables.

Cold emails going to spam?
That’s usually an inbox reputation problem, not your copy.

This n8n workflow is a complete Email Warmup Engine that helps you warm up Gmail inboxes automatically by sending natural, human-like conversations between your inboxes, spacing them out across the day, and marking messages as read to simulate real inbox activity.

It includes:

• AI-generated natural conversations (2–3 messages)
• Multi-inbox warmup (sender ↔ receiver rotation)
• Smart daily volume ramp-up (safe warmup growth)
• Random send scheduling inside a time window
• Sends + replies like a real human thread
• Marks warmup emails as read automatically
• Powered entirely by n8n Data Tables (no external DB)

Perfect for founders, agencies, SDRs, and anyone running outbound.

What This Workflow Does (Bullets)

• Generates warmup conversations using OpenAI
• Stores conversations in a Data Table
• Creates a warmup queue for each inbox daily
• Assigns random scheduled timestamps (natural behavior)
• Sends and replies via Gmail
• Updates queue status as messages are sent
• Marks warmup emails as read automatically

Use Cases

1. Warm up new inboxes before cold outreach
2. Maintain inbox health for outbound operations
3. Rotate and warm multiple sender accounts
4. Avoid paying per-inbox warmup SaaS fees

Requirements

• n8n (Cloud or Self-hosted)
• Gmail accounts (2+ recommended)
• Gmail OAuth2 credentials (one per inbox)
• OpenAI API key
• n8n Data Tables enabled
• Data Tables Used

This template uses 3 n8n Data Tables:

1. cold_email_accounts
   Stores warmup inboxes + credential IDs

2. warmup_conversations
   Stores AI-generated conversations

3. warmup_queue
   Stores scheduled warmup messages + status

Setup Instructions (Step-by-step)

1. Import the Workflow

Import the template JSON into n8n

1. Create Data Tables

Create these Data Tables:

• cold_email_accounts
• warmup_conversations
• warmup_queue

1. Add Inbox Accounts

Add at least 2 inboxes into cold_email_accounts with:

email
cred_id (Gmail OAuth credential ID)
warmup_daily_limit (ex: 5)

1. Connect Credentials

Create Gmail OAuth2 credentials in n8n for each inbox
Connect OpenAI credentials to the “Message a model” node

1. Enable Schedule Triggers

Enable all Schedule Trigger nodes so it runs automatically:

conversation generation
queue generation
sender engine
marking read engine
Customization

You can tweak:

Daily warmup growth

warmup_daily_limit in cold_email_accounts table per inbox

Time window

schedule messages between fixed hours (natural sending)

Conversation style

edit the OpenAI system prompt to match your preferred tone

Notes / Best Practices

• Keep warmup volume safe (20–40/day max per inbox)
• Use 2+ inboxes to avoid self-sending
• Don’t mix cold outreach + warmup in the same workflow