# npubmail (mcpb · npubmail-mcp-0.2.1.mcpb)

Email inbox for AI agents, owned by a Nostr key. No signup or API key. Receive codes, read, send.

- Trust score: 49/100 (low)
- Change this week: +4
- Registry status: active
- Liveness: live
- Owner verified: no
- Last scored: 2026-10-24

## Components

- mcpb · `npubmail-mcp-0.2.1.mcpb`: 49/100 (this document), [markdown](https://verifymcp.io/servers/com-npubmail-npubmail/npubmail-mcp.md), [page](https://verifymcp.io/servers/com-npubmail-npubmail/npubmail-mcp)

## Channel facts

- Registry: `mcpb`
- Package: `https://github.com/obvioussummer46/npubmail/releases/download/v0.2.1/npubmail-mcp-0.2.1.mcpb`
- Version: `0.2.1`
- Transport: `stdio`
- SHA-256: `263422516c15da4c6f577cfeb2380ce76242f188ed62e05dfb366229ad892ab9`

## 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 2026-10-24.

- **Supply Chain Security**: 0/100
  - No malware scan is available for this kind of package: the supply-chain vendors we use do not cover it. This is a permanent gap in our coverage, not a finding about the package.
  - Known CVEs could not be checked: we found no dependency list to check in this bundle: either it runs a compiled binary, whose bundled manifests we do not read, or none of the package.json, requirements.txt, pyproject.toml or uv.lock files it ships for its runtime declares a dependency we can read (a requirements.txt that only points at a setup.py project, a local path, or a nested requirements file we cannot follow counts as none).
  - Install-script risk not yet assessed.
  - Dependency health could not be checked: we found no dependency list to check in this bundle: either it runs a compiled binary, whose bundled manifests we do not read, or none of the package.json, requirements.txt, pyproject.toml or uv.lock files it ships for its runtime declares a dependency we can read (a requirements.txt that only points at a setup.py project, a local path, or a nested requirements file we cannot follow counts as none).
- **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 15 days ago).
  - Disclosure check failed: no security disclosure policy was found in the source repository.
- **Schema Quality & AI Usability**: 78/100
  - AI-judged instruction clarity (excellent).
  - Tool/resource definitions use about 1343 tokens (~83/item across 16 items; 16 tools + 0 resources), lean.
  - Usage-examples check failed: none of the tools include examples.
- **Stability & Change Management**: 67/100
  - Stability observed for 20 of 30 days with no destabilising changes; credit accrues until the full window elapses.
- **Tool Coverage**: 97/100
  - 100% of tools have a non-trivial description (not blank, and not just the tool's name).
  - 91% 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 3 tool(s) whose name or description implies an irreversible operation declare an MCP destructiveHint annotation; "delete_email" implies "delete" and declares no destructiveHint at all, which the MCP spec reads as destructive by default.
  - An AI judge read all 17 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.

**Unverified: 1 category.** A category scored 0 because we could not verify it: a data source with nothing on this package, evidence we could not reach, or a check we could not run. We only credit what we can confirm.

## Install

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

npubmail ships as an MCPB bundle, a single file you download and open in an MCP host that supports MCPB bundles, such as Claude Desktop. The host reads the launch command from the bundle's own manifest, so there is no command to copy. Before opening it, check the file's SHA-256 matches the one the MCP registry declares for it, 263422516c15da4c6f577cfeb2380ce76242f188ed62e05dfb366229ad892ab9; the commands to do that are on this page. If it does not match, do not open it.

- Download bundle: `https://github.com/obvioussummer46/npubmail/releases/download/v0.2.1/npubmail-mcp-0.2.1.mcpb`
- SHA-256: `263422516c15da4c6f577cfeb2380ce76242f188ed62e05dfb366229ad892ab9`

### Verify on macOS / Linux

```bash
echo "263422516c15da4c6f577cfeb2380ce76242f188ed62e05dfb366229ad892ab9  npubmail-mcp-0.2.1.mcpb" | shasum -a 256 -c
```

### Verify on Windows (PowerShell)

```powershell
(Get-FileHash -Algorithm SHA256 .\npubmail-mcp-0.2.1.mcpb).Hash -eq "263422516c15da4c6f577cfeb2380ce76242f188ed62e05dfb366229ad892ab9"
```

## 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.

### 2026-10-24 (score 49, +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.

### 2026-10-22 (score 48, +1)

No change was recorded against any check on this day. Stability & Change Management went from 57 to 60. That category is still filling its 30-day observation window: 17 days of observed history at the previous scan, 18 at this one. The score rises as the window fills, whether or not the server changes.

### 2026-10-20 (score 47, +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.

### 2026-10-18 (score 46, +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.

### 2026-10-16 (score 45, +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.

### 2026-10-14 (score 44, +35)

- [security improvement] Injection markers: unverified → pass
- [functional improvement] Tool coverage: unverified → 100
- [functional improvement] Stability: unverified → 0.33
- [functional improvement] MCP protocol: unverified → pass

### 2026-10-12 (score 9, 0)

- [functional] Package version: 0.2.0 → 0.2.1

### 2026-10-09 (score 9, −30)

- [security regression] Tool safety: pass → unverified
- [security] Stability: Stability not yet verified: we do not have a sandbox capture of the MCP schema this version of the package serves yet.
- [functional regression] Capabilities: pass → unverified
- [functional regression] Tool coverage: 100 → unverified
- [functional] First check of Schema quality: unverified
- [functional] Package version: 0.2.0 → 0.2.1

## MCP tools (16)

### `buy_storage` (~97 tokens)

Keep mail longer than 7 days. Answers with a Lightning invoice first; after it is paid, call again with payment_id.

Input parameters:

- `days` (integer, required): retention tier in days, e.g. 30, 90, 365 (see storage_plan)
- `months` (integer): how many 30-day periods (default 1)
- `payment_id` (string): after paying: the payment_id from the payment-required answer

### `create_alias` (~119 tokens)

Create a disposable address that delivers into your mailbox and expires. Use one per signup; set allow_from to the service's domain so nothing else can reach it. Returns a cursor for wait_for_code.

Input parameters:

- `allow_from` (string): only accept mail from these sender domains, comma-separated (e.g. github.com). Strongly recommended for signups
- `label` (string): note to self, e.g. the service you are signing up for
- `ttl_hours` (integer): hours until the address stops accepting mail (default 24)

### `delete_email` (~22 tokens)

Delete an email from your mailbox.

Input parameters:

- `id` (string, required)

### `invoice_status` (~35 tokens)

Check whether a payment request (payment_id) has been paid.

Input parameters:

- `id` (string, required): payment_id from a payment-required answer

### `list_emails` (~49 tokens)

List received emails, newest first, with extracted codes and sender verification.

Input parameters:

- `after` (string): only messages newer than this id
- `limit` (integer): max messages (default 20)

### `outbox` (~43 tokens)

Sent emails still waiting for a retry (recipient server said 'try later'), plus your bounce count. Final failures arrive in your inbox as 'Undeliverable: ...'.

### `pay_invoice` (~68 tokens)

Built-in wallet (optional): pay a Lightning invoice, within the spending limits. Paying is spending money: only pay what your principal allows. When set up, send_email pays npubmail's own invoices with it automatically (within limits).

Input parameters:

- `bolt11` (string, required): Lightning invoice to pay

### `read_email` (~58 tokens)

Read one email: text body, links (verify/confirm links flagged as action), codes, SPF/DKIM result and safety warnings.

Input parameters:

- `html` (boolean): also return the raw HTML body
- `id` (string, required): message id

### `send_email` (~203 tokens)

Send a plain-text email from your primary address. Recipients who never wrote to you cost sats: the first call answers PAYMENT REQUIRED with a Lightning invoice; after it is paid, call again with the same arguments plus payment_id. Per recipient: ok=true delivered; queued=true the receiving server asked to retry later and npubmail retries automatically for ~2 days (do not resend); ok=false without queued is a permanent failure. Daily recipient quota applies; too many bounces suspend sending. Only send what your principal asked for.

Input parameters:

- `from_name` (string): display name for the From header
- `in_reply_to` (string): Message-ID being answered, to keep threading
- `payment_id` (string): after paying a PAYMENT REQUIRED invoice for this exact message
- `reply_to` (string)
- `subject` (string, required)
- `text` (string, required): plain-text body
- `to` (null|array, required): recipient addresses (1-10)

### `set_lightning_address` (~95 tokens)

Optional. Make your mailbox addresses (name@domain, npub@domain) also work as Lightning addresses that forward to a Lightning address you already have (any wallet). npubmail only relays the lookup; payments go straight to your wallet. Empty address turns it off.

Input parameters:

- `address` (string, required): an existing Lightning address of yours (e.g. you@getalby.com), or empty to turn forwarding off

### `storage_plan` (~22 tokens)

How long your mail is kept and the prices of longer storage tiers.

### `wait_for_code` (~141 tokens)

Block until an email containing a one-time code arrives and return the code. Use the cursor from create_alias as 'after' so a code that arrives quickly is not missed.

Input parameters:

- `after` (string): cursor: only mail newer than this message id. Omit to wait for mail arriving after this call
- `from` (string): sender filter, case-insensitive substring of the From address (e.g. github.com)
- `subject` (string): subject substring filter
- `timeout_seconds` (integer): how long to wait (default 120, max 600)
- `to` (string): recipient filter, e.g. an alias address

### `wait_for_email` (~130 tokens)

Block until a matching email arrives (default 120 s) and return it. Filters: from, to, subject.

Input parameters:

- `after` (string): cursor: only mail newer than this message id. Omit to wait for mail arriving after this call
- `from` (string): sender filter, case-insensitive substring of the From address (e.g. github.com)
- `subject` (string): subject substring filter
- `timeout_seconds` (integer): how long to wait (default 120, max 600)
- `to` (string): recipient filter, e.g. an alias address

### `wallet_balance` (~22 tokens)

Built-in wallet (optional): collect incoming payments and show the balance.

### `wallet_setup` (~137 tokens)

Optional convenience: only if you have NO Lightning wallet. Sets up a small built-in ecash wallet on the same key: your Lightning address becomes <npub>@npub.cash (payments locked to your key at the Minibits Cashu mint). Spending is capped (default 100 sats per payment, 1000 per day). The mint is custodial and in beta: small amounts only. Skip this if you already have a wallet.

Input parameters:

- `forward_mailbox_addresses` (null|boolean): also make your mailbox addresses (name@domain) work as Lightning addresses pointing at this wallet, if none is set yet (default true)

### `whoami` (~24 tokens)

Your mailbox addresses (created automatically on first use) and whether sending is enabled.

## Diagnostics

Captured diagnostic sections: Provenance. The full working is on the page: https://verifymcp.io/servers/com-npubmail-npubmail/npubmail-mcp#diagnostics

## Score history

- 2026-10-24: 49
- 2026-10-23: 48
- 2026-10-22: 48
- 2026-10-21: 47
- 2026-10-20: 47
- 2026-10-19: 46
- 2026-10-18: 46
- 2026-10-17: 45
- 2026-10-16: 45
- 2026-10-15: 44
- 2026-10-14: 44
- 2026-10-13: 9
- 2026-10-12: 9
- 2026-10-10: 9
- 2026-10-09: 9
- 2026-10-07: 39
- 2026-10-04: 39

## Common questions

### What is the npubmail MCP server?

npubmail is an MCP server listed in the public MCP registry as com.npubmail/npubmail. Email inbox for AI agents, owned by a Nostr key. No signup or API key. Receive codes, read, send. This page covers its MCPB bundle (https://github.com/obvioussummer46/npubmail/releases/download/v0.2.1/npubmail-mcp-0.2.1.mcpb).

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

npubmail scores 49 out of 100 on VerifyMCP. 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 npubmail MCP server expose?

npubmail exposes 16 tools: buy_storage, create_alias, delete_email, invoice_status, list_emails, and 11 more. Their descriptions and schemas cost roughly 1,265 tokens of context every time the server is loaded.

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

npubmail 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

- Repository: https://github.com/obvioussummer46/npubmail
- Website: https://npubmail.com/
- Changelog RSS feed: https://verifymcp.io/servers/com-npubmail-npubmail/npubmail-mcp.xml
- Changelog JSON feed: https://verifymcp.io/servers/com-npubmail-npubmail/npubmail-mcp.json
- HTML version of this page: https://verifymcp.io/servers/com-npubmail-npubmail/npubmail-mcp