Connecting Evermail to ChatGPT and OpenAI
Evermail runs a remote MCP server that any MCP-capable tool can call. How you connect depends on which OpenAI product you're using — and one of them can't connect yet. Here's the honest breakdown.
What works today
Evermail's MCP server authenticates with an API key sent as an X-API-Key request header. Whether a tool can send that header decides everything below.
| Where you want to use it | Status |
|---|---|
| OpenAI API (Responses API, your own code) | Works today — jump to setup |
| ChatGPT web app (chatgpt.com, developer mode) | Not yet — why, and what we're doing |
| Claude Code | Works today — see Connecting Claude |
You'll need an Evermail API key for any of these. Create one at app.evermail.ai/settings/integrations — click Create API key, name it something like "ChatGPT", and copy the value starting with em_live_ immediately. It's only shown once. API keys require a Starter, Pro, Team, or Enterprise plan; see Billing & Plans.
OpenAI API — Responses API
If you're building something with OpenAI's API, you can hand it the Evermail MCP server directly. The Responses API accepts custom headers, so our API key works without any extra plumbing.
Add Evermail as an MCP tool
Pass an mcp tool in your request, with your Evermail key in the headers map:
{
"model": "gpt-5.6",
"input": "Find the Henderson contract from 2019 in my archive",
"tools": [
{
"type": "mcp",
"server_label": "evermail",
"server_url": "https://mcp.evermail.ai/mcp",
"headers": { "X-API-Key": "em_live_your_key_here" },
"require_approval": "never"
}
]
}Optionally narrow the tools
Evermail exposes eight tools. If you only want the model to search and read — never export — restrict it with allowed_tools:
"allowed_tools": ["search_emails", "get_email", "list_mailboxes"]Keep the key server-side
The request above contains a credential that grants full read access to your entire archive. Send it from your backend — never from browser or mobile client code.
Model names and API shapes change. Check OpenAI's current MCP and connectors guide before you build — the field we rely on here is headers on the MCP tool object.
ChatGPT web app
You can add custom MCP servers to ChatGPT through developer mode — but not ours, yet. Here's exactly why, so you don't spend an afternoon looking for a setting that isn't there.
ChatGPT's custom connectors support two authentication schemes: no authentication and OAuth. There is no field anywhere in the ChatGPT interface for entering a custom request header, so there is nowhere to put an Evermail API key. This isn't a plan restriction or a rollout you can request early access to — the capability doesn't exist in the product.
We're not going to suggest the obvious workaround, either: making the Evermail MCP server reachable without authentication would expose your archive to anyone who guessed the URL. That's not a trade we'll make.
What we're doing about it: we're adding OAuth support to the Evermail MCP server. OAuth is supported by ChatGPT and by Claude's web and desktop apps, and it's better security than a shared API key — each person signs in as themselves and grants access explicitly, and you can revoke one person without rotating a key everyone shares. We'll update this page when it ships. If you want to be told directly, email support@evermail.ai and we'll add you to the list.
In the meantime, if your goal is to ask questions about your archive in a chat interface, Claude Code works today and takes about two minutes to set up.
Any other MCP client
The test is simple: can the tool send a custom HTTP header with its MCP requests? If yes, it can connect to Evermail today.
Evermail's server speaks the Streamable HTTP transport. The legacy HTTP+SSE transport is not enabled, so don't point a client at /sse. If your tool accepts a raw mcpServers configuration block, use this:
{
"mcpServers": {
"evermail": {
"type": "http",
"url": "https://mcp.evermail.ai/mcp",
"headers": { "X-API-Key": "em_live_your_key_here" }
}
}
}Our server is reached from the AI provider's cloud, not from your computer — so it has to be publicly reachable, which mcp.evermail.ai is. Nothing needs opening on your network.
Common errors
| Error | What it means |
|---|---|
401 Unauthorized | The API key is missing, wrong, or revoked — or the account is on the Free plan, which can't create API keys. Create a fresh key at Settings → Integrations. |
403 Forbidden | The key is valid but the plan no longer includes MCP access. Check Settings → Billing. |
404 Not Found | The URL is wrong. It must be exactly https://mcp.evermail.ai/mcp — no trailing slash, and not /sse. |
429 Too Many Requests | Rate limit of 20 requests per minute per IP address. Wait a minute and retry. |
What the API key can do
An Evermail API key grants full read access to your workspace's entire archive — anything you or a teammate could search or open in the Evermail app, a connected AI tool can too. Treat it like a password: don't share it, don't commit it to a repository, and don't put it in client-side code. Revoke a key at any time from Settings → Integrations; that immediately cuts off anything using it.
Evermail only sends the specific emails a tool call asks for. What the AI provider does with data you send it is governed by their privacy policy, not ours.
Ready to connect?
Create an API key, then wire up the Responses API — or use Claude Code today.
Create an API key →