# MailerCheck MCP by usefulapi (remote · mailercheck.usefulapi.io)

Check MailerCheck credits and lists, and run confirmed asynchronous email verification.

- Trust score: 18/100 (low)
- Change this week: −42
- Registry status: active
- Liveness: live
- Owner verified: no
- Last scored: 2026-11-05

## Components

- remote · `mailercheck.usefulapi.io`: 18/100 (this document), [markdown](https://verifymcp.io/servers/io-usefulapi-mailercheck/mailercheck.md), [page](https://verifymcp.io/servers/io-usefulapi-mailercheck/mailercheck)

## Channel facts

- Endpoint: `https://mailercheck.usefulapi.io/mcp`
- Transports: `streamable-http`
- Auth: `none`
- Version: `1.6.3`

## Trust breakdown

How this component scores in each security and reliability category. Every signal is checked automatically against the live server, 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 2026-11-05.

- **Endpoint Security**: 46/100
  - The endpoint's TLS certificate is valid, in date, and uses a strong key.
  - Authorisation not yet verified: we couldn't confirm whether this endpoint requires it.
  - HTTPS enforcement could not be verified: the plaintext port redirected somewhere other than https, so enforcement is unproven.
  - HSTS check failed: the Strict-Transport-Security header is absent.
  - DNSSEC check failed: this domain isn't protected by DNSSEC.
- **Transport & Reachability**: 0/100
  - Transport check failed: declared streamable-http, but the endpoint redirected instead of responding directly.
- **Schema Quality & AI Usability**: 0/100
  - Schema not yet verified: we couldn't read the endpoint's schema, or could read only part of its tool list.
- **Stability & Change Management**: 0/100
  - Stability not yet verified: not enough scan history yet (needs a 30-day window).
- **Tool Coverage**: 0/100
  - Tool coverage not yet verified: we couldn't read the endpoint's tools, or could read only part of the list.
- **Tool Safety**: 0/100
  - Tool safety not yet verified: we couldn't read the endpoint's tools, or could read only part of the list.
- **Capabilities**: 0/100
  - Capabilities not yet verified: we couldn't read the endpoint's capabilities.

**Unverified: 5 categories.** Categories scored 0 because we could not verify them: authentication we do not have, an unreachable endpoint, or not enough scan history. We only credit what we can confirm.

## Install

### How do I install the MailerCheck MCP by usefulapi server?

MailerCheck MCP by usefulapi is a hosted endpoint at https://mailercheck.usefulapi.io/mcp, so there is nothing to install locally. 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 --transport http io-usefulapi-mailercheck 'https://mailercheck.usefulapi.io/mcp'
```

### Cursor

```json
{
  "mcpServers": {
    "io-usefulapi-mailercheck": {
      "url": "https://mailercheck.usefulapi.io/mcp"
    }
  }
}
```

### VS Code

```json
{
  "servers": {
    "io-usefulapi-mailercheck": {
      "type": "http",
      "url": "https://mailercheck.usefulapi.io/mcp"
    }
  }
}
```

### Codex

```toml
[mcp_servers.io-usefulapi-mailercheck]
url = "https://mailercheck.usefulapi.io/mcp"
```

### opencode

```json
{
  "$schema": "https://opencode.ai/config.json",
  "mcp": {
    "io-usefulapi-mailercheck": {
      "type": "remote",
      "url": "https://mailercheck.usefulapi.io/mcp",
      "enabled": true
    }
  }
}
```

### OpenClaw

```bash
openclaw mcp add io-usefulapi-mailercheck --url 'https://mailercheck.usefulapi.io/mcp' --transport streamable-http
```

### Hermes

```yaml
mcp_servers:
  io-usefulapi-mailercheck:
    url: "https://mailercheck.usefulapi.io/mcp"
```

### Netclaw

```json
{
  "McpServers": {
    "io-usefulapi-mailercheck": {
      "Transport": "http",
      "Url": "https://mailercheck.usefulapi.io/mcp"
    }
  }
}
```

### Vellum

```bash
assistant mcp add io-usefulapi-mailercheck -t streamable-http -u 'https://mailercheck.usefulapi.io/mcp'
```

### Other

```json
{
  "mcpServers": {
    "io-usefulapi-mailercheck": {
      "type": "http",
      "url": "https://mailercheck.usefulapi.io/mcp"
    }
  }
}
```

The mcpServers block is a cross-client convention. Remote transports vary, so check your client's docs.

## 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.

### 2026-11-02 (score 18, −46)

- [security regression] Endpoint reachability: reachable → not serving MCP
- [security regression] Stability: 0.10 → unverified
- [security regression] Tool safety: pass → unverified
- [security regression] Authorization: pass → unverified
- [functional regression] Schema quality: 100 → unverified
- [functional regression] Capabilities: pass → unverified
- [functional regression] Tool coverage: 100 → unverified

### 2026-10-31 (score 64, +4)

- [security improvement] Authorization: partial → pass
- [functional improvement] MCP protocol: fail → pass
- [functional] New prompt “check_verification_capacity”
- [functional] New prompt “review_list_verification_progress”
- [functional] New prompt “verify_a_new_email_address”
- [functional] MCP protocol version: 2025-06-18 → 2025-11-25
- [functional] Server version: 1.2.0 → 1.4.0
- [functional] Server version: 1.1.0 → 1.2.0
- [functional] Server version: 1.0.3 → 1.1.0

### 2026-10-30 (score 60, 0)

- [functional improvement] Stability: unverified → 0.03
- [functional] Server version: 1.0.2 → 1.0.3
- [functional] Server version: 1.0.1 → 1.0.2

### 2026-10-29 (score 60)

First indexed and scored.

## MCP tools (6)

### `mailercheck_account` (~33 tokens)

Read MailerCheck account

Read the connected MailerCheck account name, ID and credit balance. Does not verify emails or spend verification credits.

### `mailercheck_credits` (~24 tokens)

Check MailerCheck credits

Read the available MailerCheck verification credit balance without starting verification.

### `mailercheck_lists` (~61 tokens)

List MailerCheck verification lists

Read one bounded page of list summaries, processing status and statistics. Does not create, verify or delete lists. Pagination stays on the MailerCheck API; no response links are followed.

Input parameters:

- `limit` (integer)
- `page` (integer)

### `mailercheck_get_list` (~38 tokens)

Read MailerCheck list status

Read one existing list's verification status and aggregate result counts. Does not start or restart verification.

Input parameters:

- `list_id` (string, required)

### `mailercheck_verify_email` (~81 tokens)

Start MailerCheck email verification

Submit one email for asynchronous verification. Spends MailerCheck credits and requires confirm:true. This call is never retried. Read the returned verification ID with mailercheck_verification_result; wait between polls. If the response is lost, check MailerCheck before submitting again.

Input parameters:

- `confirm` (boolean)
- `email` (string, required)

### `mailercheck_verification_result` (~53 tokens)

Read MailerCheck email verification result

Read the status and result of a previously submitted asynchronous email check. Does not start new verification. Call once and wait before polling again; no automatic polling is performed.

Input parameters:

- `verification_id` (string, required)

## Diagnostics

Captured diagnostic sections: TLS, DNSSEC, Authorisation, Transports. The full working is on the page: https://verifymcp.io/servers/io-usefulapi-mailercheck/mailercheck#diagnostics

## Score history

- 2026-11-05: 18
- 2026-11-04: 18
- 2026-11-03: 18
- 2026-11-02: 18
- 2026-11-01: 64
- 2026-10-31: 64
- 2026-10-30: 60
- 2026-10-29: 60

## Common questions

### What is the MailerCheck MCP by usefulapi server?

MailerCheck MCP by usefulapi is listed in the public MCP registry as io.usefulapi/mailercheck. Check MailerCheck credits and lists, and run confirmed asynchronous email verification. This page covers its hosted endpoint (https://mailercheck.usefulapi.io/mcp).

### Is the MailerCheck MCP by usefulapi server safe to use?

MailerCheck MCP by usefulapi scores 18 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 MailerCheck MCP by usefulapi server expose?

MailerCheck MCP by usefulapi exposes 6 tools: mailercheck_account, mailercheck_credits, mailercheck_lists, mailercheck_get_list, mailercheck_verify_email, mailercheck_verification_result. Their descriptions and schemas cost roughly 290 tokens of context every time the server is loaded.

### Does the MailerCheck MCP by usefulapi server require authentication?

Its publisher declares no required credentials for MailerCheck MCP by usefulapi. We have not been able to confirm that against the live endpoint, and a server can require authorisation without declaring it here.

### Is the MailerCheck MCP by usefulapi server still maintained?

MailerCheck MCP by usefulapi is still listed as active in the MCP registry. We last reached this channel on 5 November 2026. Those dates come from our own scans of the registry and the channel itself, not from anything the publisher announced.

### What did VerifyMCP test on the MailerCheck MCP by usefulapi server?

VerifyMCP ran 4 checks on MailerCheck MCP by usefulapi, covering TLS certificate, HSTS header, DNSSEC and Transport. 7 items could not be completed, a gap on our side rather than a finding about MailerCheck MCP by usefulapi: Authorization, HTTPS, Schema quality, Stability and 3 more. 5 categories score 0 for that reason, because we only credit what we can confirm. Supply Chain Security and Provenance & Transparency do not apply to a hosted endpoint, so they were not tested. The score does not measure everything, and the scoring documentation lists what it leaves out.

## Links

- Remote endpoint: https://mailercheck.usefulapi.io/mcp
- Repository: https://github.com/m190/usefulapi-mcp
- Website: https://usefulapi.io/mailercheck/
- Changelog RSS feed: https://verifymcp.io/servers/io-usefulapi-mailercheck/mailercheck.xml
- Changelog JSON feed: https://verifymcp.io/servers/io-usefulapi-mailercheck/mailercheck/changelog.json
- Trust report (JSON): https://verifymcp.io/servers/io-usefulapi-mailercheck/mailercheck.json
- HTML version of this page: https://verifymcp.io/servers/io-usefulapi-mailercheck/mailercheck