Skip to main content

ChatGPT

ChatGPT supports Custom MCP connectors on Plus, Pro, Business, Enterprise and Edu. You enable Developer Mode once to add the app — after that you can turn Developer Mode back off, and the connector stays in place and keeps working.

Full MCP support including write actions is currently rolling out on Business, Enterprise and Edu. Read access works reliably on Plus and Pro; write tools are still partially gated.

Setup​

1. Copy the MCP URL from the portal​

In the inboxmcp portal under Integrations you'll find your MCP URL — format: https://mcp.inboxmcp.io/mcp.

2. Enable Developer Mode in ChatGPT​

Open ChatGPT's settings and switch to Apps on the left. On the right, click Advanced settings.

ChatGPT settings with the 'Apps' section selected. On the right, the 'Advanced settings' entry.
ChatGPT settings → "Apps" → "Advanced settings".

Flip the Developer Mode switch. The "Increased risk" warning is OpenAI's standard notice for connectors they haven't verified themselves — it applies to every custom MCP server the same way.

Advanced settings with the 'Developer Mode' switch enabled and an 'Increased risk' warning.
Enable Developer Mode.

3. Create the app​

Back in the Apps section. Next to "Advanced settings" you'll now see a Create app button — click it.

Apps overview, the mouse pointer is on the 'Create app' button.
In the Apps section, click "Create app".

In the New app dialog, fill in:

  • Name: e.g. inboxmcp.io
  • MCP server URL: the MCP URL from step 1, i.e. https://mcp.inboxmcp.io/mcp
  • Authentication: OAuth
  • Confirm the risk notice and click Create
'New app' dialog with the fields name, MCP server URL and authentication. Below, the 'Custom MCP servers carry risks' notice with confirmation checkbox.
Create the new app — paste the MCP URL, pick OAuth, confirm the risk.

ChatGPT then opens the OAuth flow in your browser. Sign in to inboxmcp and confirm access — the app is set up.

4. (Optional) Turn Developer Mode off again​

Once the app is created, you can switch Developer Mode off again under Advanced settings. The inboxmcp app stays connected under Active apps and keeps working.

What ChatGPT can do now​

  • List and search mailboxes
  • Read individual messages, including attachments
  • With Premium / Business: create drafts, move messages, manage folders

The tools available depend on your inboxmcp plan — see MCP tools overview.

Disconnect​

In ChatGPT: Settings → Apps → inboxmcp.io → Remove. This invalidates the OAuth token on the inboxmcp side; further access is blocked immediately.

Notes​

  • Plan requirements: Plus, Pro, Business, Enterprise, Edu. The free plan does not currently offer this feature.
  • App directory: inboxmcp is in review for OpenAI's official app directory in parallel. Once the listing is live, inboxmcp can be installed from there without Developer Mode — status on the roadmap.