# MailFlat (pypi · mailflat-mcp)

Real email inboxes for AI agents: open an address, read the one-time code, send mail.

- Trust score: 76/100 (medium)
- Change this week: +3
- Registry status: active
- Liveness: live
- Owner verified: no
- Last scored: 2026-09-20

## Components

- pypi · `mailflat-mcp`: 76/100 (this document), [markdown](https://verifymcp.io/servers/mailflat-mailflat-mcp/mailflat-mcp.md), [page](https://verifymcp.io/servers/mailflat-mailflat-mcp/mailflat-mcp)

## Channel facts

- Registry: `pypi`
- Package: `mailflat-mcp`
- Version: `0.9.2`
- Transport: `stdio`

## Trust breakdown

How this component scores in each security and reliability category. Every signal is checked automatically from public evidence about the published package, including repeated runs of it in an isolated sandbox, and we only credit what we can confirm. Scores are 0–100 per category. Scoring method: https://verifymcp.io/docs/scoring (what has changed: https://verifymcp.io/docs/scoring/changelog)

Scored 2026-09-20.

- **Supply Chain Security**: 100/100
  - No malware found by supply-chain analysis.
  - No known CVEs affecting this package version or its production dependencies.
  - Runs hatchling.build at install time, a recognised native-build step with no shell scripting around it.
  - 0 of 30 dependencies flagged as unhealthy.
- **Provenance & Transparency**: 45/100
  - Source repository is publicly reachable at the declared URL.
  - Provenance check failed: no build-provenance attestation is published.
  - Clear OSI-approved license (MIT).
  - Actively maintained (last published 23 days ago).
  - Disclosure check failed: no security disclosure policy was found in the source repository.
- **Schema Quality & AI Usability**: 69/100
  - AI-judged instruction clarity (good).
  - Tool/resource definitions use about 986 tokens (~82/item across 12 items; 12 tools + 0 resources), lean.
  - Usage-examples check failed: none of the tools include examples.
- **Stability & Change Management**: 80/100
  - Stability observed for 24 of 30 days with no destabilising changes; credit accrues until the full window elapses.
- **Tool Coverage**: 67/100
  - 100% of tools have a non-trivial description (not blank, and not just the tool's name).
  - 0% of tool parameters carry a description.
- **Tool Safety**: 75/100
  - No prompt-injection markers were found in the server instructions, tool names or descriptions we captured.
  - 0 of 4 tool(s) whose name or description implies an irreversible operation declare an MCP destructiveHint annotation; "send_email" implies "send" and declares no destructiveHint at all, which the MCP spec reads as destructive by default.
  - An AI judge read all 12 captured unit(s) of tool text and found none that tries to manipulate the model reading it.
- **Capabilities**: 100/100
  - Implements a supported MCP spec version (2025-11-25); the latest is 2026-07-28.

## Install

### How do I install the MailFlat MCP server?

MailFlat runs locally as a PyPI package, launched with uvx mailflat-mcp. Ready-made configuration for Claude, Cursor, VS Code, Codex and 5 more is on this page, copied from each client's own documentation.

### Claude

```bash
claude mcp add mailflat-mailflat-mcp -- uvx mailflat-mcp
```

### Cursor

```json
{
  "mcpServers": {
    "mailflat-mailflat-mcp": {
      "command": "uvx",
      "args": [
        "mailflat-mcp"
      ]
    }
  }
}
```

### VS Code

```json
{
  "servers": {
    "mailflat-mailflat-mcp": {
      "command": "uvx",
      "args": [
        "mailflat-mcp"
      ]
    }
  }
}
```

### Codex

```bash
codex mcp add mailflat-mailflat-mcp -- uvx mailflat-mcp
```

### opencode

```json
{
  "$schema": "https://opencode.ai/config.json",
  "mcp": {
    "mailflat-mailflat-mcp": {
      "type": "local",
      "command": [
        "uvx",
        "mailflat-mcp"
      ],
      "enabled": true
    }
  }
}
```

### OpenClaw

```bash
openclaw mcp add mailflat-mailflat-mcp --command uvx --arg mailflat-mcp
```

### Hermes

```yaml
mcp_servers:
  mailflat-mailflat-mcp:
    command: "uvx"
    args: ["mailflat-mcp"]
```

### Netclaw

```json
{
  "McpServers": {
    "mailflat-mailflat-mcp": {
      "Transport": "stdio",
      "Command": "uvx",
      "Arguments": [
        "mailflat-mcp"
      ]
    }
  }
}
```

### Vellum

```bash
assistant mcp add mailflat-mailflat-mcp -t stdio -c uvx -a mailflat-mcp
```

### Other

```json
{
  "mcpServers": {
    "mailflat-mailflat-mcp": {
      "command": "uvx",
      "args": [
        "mailflat-mcp"
      ]
    }
  }
}
```

## Changelog

Every change recorded for this component, newest first. Days that predate change tracking, or that we cannot explain, say so: "we were watching and nothing happened" and "we were not watching" are different claims.

### 2026-09-18 (score 76, +1)

No change was recorded against any check on this day. Stability & Change Management went from 70 to 73. That category is still filling its 30-day observation window: 21 days of observed history at the previous scan, 22 at this one. The score rises as the window fills, whether or not the server changes.

### 2026-09-16 (score 75, +1)

No change was recorded against any check on this day. Stability & Change Management went from 63 to 67. That category is still filling its 30-day observation window: 19 days of observed history at the previous scan, 20 at this one. The score rises as the window fills, whether or not the server changes.

### 2026-09-15 (score 74, +15)

- [security improvement] Malware scan: unverified → pass

### 2026-09-14 (score 59, −14)

- [security regression] Malware scan: pass → unverified

### 2026-09-12 (score 73, +1)

No change was recorded against any check on this day. Stability & Change Management went from 50 to 53. That category is still filling its 30-day observation window: 15 days of observed history at the previous scan, 16 at this one. The score rises as the window fills, whether or not the server changes.

### 2026-09-10 (score 72, +1)

No change was recorded against any check on this day. Stability & Change Management went from 43 to 47. That category is still filling its 30-day observation window: 13 days of observed history at the previous scan, 14 at this one. The score rises as the window fills, whether or not the server changes.

### 2026-09-08 (score 71, +1)

No change was recorded against any check on this day. Stability & Change Management went from 37 to 40. That category is still filling its 30-day observation window: 11 days of observed history at the previous scan, 12 at this one. The score rises as the window fills, whether or not the server changes.

### 2026-09-06 (score 70, +1)

No change was recorded against any check on this day. Stability & Change Management went from 30 to 33. That category is still filling its 30-day observation window: 9 days of observed history at the previous scan, 10 at this one. The score rises as the window fills, whether or not the server changes.

## MCP tools (12)

### `create_inbox` (~148 tokens)

Open an email inbox and return its address. Use this when you need an address to sign
up for a service or to receive a one-time code.

The address is permanent and stays until you delete it, so a test suite can reuse one
address across runs instead of opening a new inbox each time. Only the messages inside
expire, on the retention window you choose.

\`label` needs a paid plan; on free it is reported back in `ignored_fields`.
\`retention_hours` is optional (0 = your plan's max); requests above your plan are capped.

Input parameters:

- `label` (string)
- `prefix` (string)
- `retention_hours` (integer)

### `list_inboxes` (~19 tokens)

List all inboxes available to this API key.

### `read_messages` (~89 tokens)

Read messages in the given inbox address (newest first).

\`direction` is "in" for received mail (default), "out" for mail sent from this
address, or "all" for both. Received mail is the default so that a reply you are
waiting for is not confused with a message you just sent.

Input parameters:

- `address` (string, required)
- `direction` (string)

### `wait_for_otp` (~43 tokens)

Poll the inbox until an OTP code arrives (or timeout). Returns {otp_code, email}.

Input parameters:

- `address` (string, required)
- `timeout` (integer)

### `wait_for_message` (~67 tokens)

Poll the inbox until a new message ARRIVES (or timeout). Returns {email}.

Only received mail counts, so you can send to a peer and then wait for their reply
without matching your own outgoing message.

Input parameters:

- `address` (string, required)
- `timeout` (integer)

### `send_email` (~161 tokens)

Send an email FROM the given inbox address (DKIM-signed via MailFlat's MTA).
Use for replies or outbound automation. `html` is optional.

Returns once the mail is ACCEPTED for delivery, not once it is delivered: delivery
runs on a queue and the result arrives via webhook or by reading the message back.

\`cc` addresses appear in the mail's headers; `bcc` addresses never do — not even in
their own copy. Attachments are not available here; send those from the SDK.

Input parameters:

- `address` (string, required)
- `bcc`
- `body` (string)
- `cc`
- `html` (string)
- `subject` (string)
- `to` (string, required)

### `reply` (~107 tokens)

Reply to a message so it stays in the SAME conversation.

Prefer this over send_email when answering: it fills in the recipient, an `Re:` subject
and the threading headers. A plain send_email starts a new conversation in the
recipient's client, which does not look like a reply.

Input parameters:

- `address` (string, required)
- `bcc`
- `body` (string)
- `cc`
- `html` (string)
- `message_id` (integer, required)

### `wait_until_sent` (~207 tokens)

Find out whether a mail you sent was actually delivered.

send_email only means "accepted for delivery"; the mail goes out later on a queue. Call
this with the message_id send_email returned to learn the outcome.

Returns `delivered: true` once it went out. If it is still queued when the timeout
elapses you get `timed_out: true` with `delivered: false` — that is NOT a failure and
you must NOT send the mail again; the queue is still retrying. `status` tells you
whether it has been attempted yet (`queued`) or attempted and rescheduled (`retrying`),
and `error` carries what the last attempt reported. Permanent failure comes back the
same way, as `status: failed` with the reason in `error` — read `note` before you
resend anything.

Input parameters:

- `address` (string, required)
- `message_id` (integer, required)
- `timeout` (integer)

### `mark_read` (~35 tokens)

Mark one message as read so later polls can skip it.

Input parameters:

- `address` (string, required)
- `message_id` (integer, required)

### `burn_inbox` (~41 tokens)

Delete every message in an inbox but KEEP the address.

Use between scenarios: the address stays registered wherever you already used it.

Input parameters:

- `address` (string, required)

### `delete_inbox` (~30 tokens)

Delete an inbox and all its messages by address. Irreversible.

Input parameters:

- `address` (string, required)

### `delete_message` (~39 tokens)

Delete a single message in an inbox by its id (the inbox itself stays).

Input parameters:

- `address` (string, required)
- `message_id` (integer, required)

## Diagnostics

Captured diagnostic sections: Provenance, Install scripts, Dependencies. The full working is on the page: https://verifymcp.io/servers/mailflat-mailflat-mcp/mailflat-mcp#diagnostics

## Score history

- 2026-09-20: 76
- 2026-09-19: 76
- 2026-09-18: 76
- 2026-09-17: 75
- 2026-09-16: 75
- 2026-09-15: 74
- 2026-09-14: 59
- 2026-09-13: 73
- 2026-09-12: 73
- 2026-09-11: 72
- 2026-09-10: 72
- 2026-09-09: 71
- 2026-09-08: 71
- 2026-09-07: 70
- 2026-09-06: 70
- 2026-09-05: 69
- 2026-09-04: 69
- 2026-09-03: 65
- 2026-09-02: 65
- 2026-09-01: 65
- 2026-08-31: 65
- 2026-08-30: 65
- 2026-08-29: 65
- 2026-08-28: 65
- 2026-08-27: 50

## Common questions

### What is the MailFlat MCP server?

MailFlat is an MCP server listed in the public MCP registry as io.github.MailFlat/mailflat-mcp. Real email inboxes for AI agents: open an address, read the one-time code, send mail. This page covers its PyPI package (mailflat-mcp).

### Is the MailFlat MCP server safe to use?

MailFlat scores 76 out of 100 on VerifyMCP. We found no known CVEs affecting it as of 20 September 2026. That is a record of what we were able to check automatically, not an endorsement. The category breakdown on this page shows every signal behind the number, including the ones we could not confirm.

### What tools does the MailFlat MCP server expose?

MailFlat exposes 12 tools: create_inbox, list_inboxes, read_messages, wait_for_otp, wait_for_message, and 7 more. Their descriptions and schemas cost roughly 986 tokens of context every time the server is loaded.

### Is the MailFlat MCP server still maintained?

MailFlat is still listed as active in the MCP registry. We last reached this channel on 20 September 2026. Those dates come from our own scans of the registry and the channel itself, not from anything the publisher announced.

### What licence is the MailFlat MCP server under?

MailFlat declares the MIT licence, which is OSI-approved. That covers the source only, and says nothing about the cost of any service it calls.

## Links

- PyPI project: https://pypi.org/project/mailflat-mcp/
- Socket report: https://socket.dev/pypi/package/mailflat-mcp
- Repository: https://github.com/MailFlat/mailflat-sdks
- Website: https://mailflat.net/docs/ai/mcp
- Changelog RSS feed: https://verifymcp.io/servers/mailflat-mailflat-mcp/mailflat-mcp.xml
- Changelog JSON feed: https://verifymcp.io/servers/mailflat-mailflat-mcp/mailflat-mcp.json
- HTML version of this page: https://verifymcp.io/servers/mailflat-mailflat-mcp/mailflat-mcp