MailerCheck MCP by usefulapi
REMOTE · MAILERCHECK.USEFULAPI.IO
Check MailerCheck credits and lists, and run confirmed asynchronous email verification.
Available components
Last scanned (4 hours ago)
Scores higher than 4% of remote servers
Reachable. Last reached 5 Nov 2026.
Category Marketing and SEO
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. How we score → Why this is hard to score →
Endpoint Security46
- The endpoint's TLS certificate is valid, in date, and uses a strong key. View diagnostics → Pass
- Authorisation not yet verified: we couldn't confirm whether this endpoint requires it. View diagnostics → Unverified
- HTTPS enforcement could not be verified: the plaintext port redirected somewhere other than https, so enforcement is unproven. View diagnostics → Unverified
- HSTS check failed: the Strict-Transport-Security header is absent. See how to fix → View diagnostics → Fail
- DNSSEC check failed: this domain isn't protected by DNSSEC. See how to fix → View diagnostics → Fail
Transport & Reachability0
- Transport check failed: declared streamable-http, but the endpoint redirected instead of responding directly. See how to fix → View diagnostics → Fail
Schema Quality & AI Usability0
- Schema not yet verified: we couldn't read the endpoint's schema, or could read only part of its tool list.Unverified
Stability & Change Management0
- Stability not yet verified: not enough scan history yet (needs a 30-day window).Unverified
Tool Coverage0
- Tool coverage not yet verified: we couldn't read the endpoint's tools, or could read only part of the list.Unverified
Tool Safety0
- Tool safety not yet verified: we couldn't read the endpoint's tools, or could read only part of the list.Unverified
Capabilities0
- Capabilities not yet verified: we couldn't read the endpoint's capabilities.Unverified
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.
Checks we ran (4)
- TLS certificate
- HSTS header
- DNSSEC
- Transport
Checks we could not complete (7)
These are gaps on our side, not findings about this hosted endpoint. We only credit what we can confirm, so a category made up entirely of them scores 0.
- Authorization in Endpoint SecurityAuthorisation not yet verified: we couldn't confirm whether this endpoint requires it.
- HTTPS in Endpoint SecurityHTTPS enforcement could not be verified: the plaintext port redirected somewhere other than https, so enforcement is unproven.
- Schema quality in Schema Quality & AI Usability (scores 0 for this)Schema not yet verified: we couldn't read the endpoint's schema, or could read only part of its tool list.
- Stability in Stability & Change Management (scores 0 for this)Stability not yet verified: not enough scan history yet (needs a 30-day window).
- Tool coverage in Tool Coverage (scores 0 for this)Tool coverage not yet verified: we couldn't read the endpoint's tools, or could read only part of the list.
- Tool safety in Tool Safety (scores 0 for this)Tool safety not yet verified: we couldn't read the endpoint's tools, or could read only part of the list.
- Capabilities in Capabilities (scores 0 for this)Capabilities not yet verified: we couldn't read the endpoint's capabilities.
Does not apply to this hosted endpoint (2)
- Supply Chain SecurityScored on package channels only. This is a hosted endpoint, so there is nothing to install or inspect.
- Provenance & TransparencyScored on package channels only. This is a hosted endpoint, so there is nothing to install or inspect.
The score does not measure everything. What the score does not measure →
Every change we have recorded for this component, newest first. Security-relevant changes are always shown. ▲ marks a change for the better, ▼ a change for the worse; unmarked changes are neutral.
- 2 Nov 26 −46
- Endpoint reachability: reachable → not serving MCP ▼ security
- Stability: 0.10 → unverified ▼ security
- Tool safety: pass → unverified ▼ security
- Authorization: pass → unverified ▼ security
- Schema quality: 100 → unverified ▼ functional
- Capabilities: pass → unverified ▼ functional
- Tool coverage: 100 → unverified ▼ functional
- 31 Oct 26 +4
- Authorization: partial → pass ▲ security
- 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 functional
- 30 Oct 26 0
- Stability: unverified → 0.03 ▲ functional
- Server version: 1.0.2 → 1.0.3 functional
- Server version: 1.0.1 → 1.0.2 functional
- 29 Oct 26 60
First indexed and scored.
Diagnostic detail from the automated scan of this channel: what the scanner observed at each step, so you can see exactly where a check passed or failed. It is informational only and never changes the trust score.
Captured 5 Nov 2026 · Probed https://mailercheck.usefulapi.io/mcp
TLS valid
Negotiated TLS 1.3 with TLS_AES_128_GCM_SHA256 .
| Subject | Issuer | Valid from | Valid until | Key | Signature | Serial |
|---|---|---|---|---|---|---|
| CN=usefulapi.io | CN=WE1,O=Google Trust Services,C=US | 13 Sept 2026 | 12 Dec 2026 | ECDSA 256 | ECDSA-SHA256 | d9be3287b0fde9630e825ba1f79bff3f |
| SANs: usefulapi.io, *.usefulapi.io | ||||||
| CN=WE1,O=Google Trust Services,C=US (CA) | CN=GTS Root R4,O=Google Trust Services LLC,C=US | 13 Dec 2023 | 20 Feb 2029 | ECDSA 256 | ECDSA-SHA384 | 7ff31977972c224a76155d13b6d685e3 |
| CN=GTS Root R4,O=Google Trust Services LLC,C=US (CA) | CN=GlobalSign Root CA,OU=Root CA,O=GlobalSign nv-sa,C=BE | 15 Nov 2023 | 28 Jan 2028 | ECDSA 384 | SHA256-RSA | 7fe530bf331343bedd821610493d8a1b |
Background: What to check on a remote MCP endpoint →
DNSSEC insecure
Validation of mailercheck.usefulapi.io. — Not signed
| Zone | DS | Keys | Algorithms | Outcome |
|---|---|---|---|---|
| . | Trust anchor | 20326, 38696 | 8, 8 | Verified |
| io. | DS published | 38690 | 8 | Verified |
| usefulapi.io. | No DS | Unsigned (proven) parent-signed NSEC/NSEC3 proves an unsigned delegation |
Authentication Inconclusive
We could not reach the endpoint well enough to judge its authorisation posture.
| Result | Inconclusive |
|---|---|
| HTTP status | 302 |
Background: How OAuth 2.1 works in the 2026 MCP spec →
Transports 2 probes
| Transport | URL | Outcome | Status | Location |
|---|---|---|---|---|
| streamable-http | https://mailercheck.usefulapi.io/mcp | Redirected | 302 | https://usefulapi.io/mailercheck/ |
| http (plaintext) | http://mailercheck.usefulapi.io/mcp | Inconclusive | 302 | http://mailercheck.usefulapi.io/mcp |
The tools this component advertises to a client, with an estimated token cost for each. Expand a tool to see its parameters and schema. The per-tool counts are indicative and are not scored directly; the schema's total context footprint is one signal in Schema Quality & AI Usability. A tool's description is untrusted text the model reads on every call, which is what makes this list a security surface and not just an inventory: how tool poisoning works →
mailercheck_account Read MailerCheck account ~33
Read the connected MailerCheck account name, ID and credit balance. Does not verify emails or spend verification credits.
Input schema present but exposes no named parameters.
No output schema declared.
No examples provided.
mailercheck_credits Check MailerCheck credits ~24
Read the available MailerCheck verification credit balance without starting verification.
Input schema present but exposes no named parameters.
No output schema declared.
No examples provided.
mailercheck_get_list Read MailerCheck list status ~38
Read one existing list's verification status and aggregate result counts. Does not start or restart verification.
| Name | Type | Req | Description |
|---|---|---|---|
| list_id | string | yes | – |
No output schema declared.
No examples provided.
mailercheck_lists List MailerCheck verification lists ~61
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.
| Name | Type | Req | Description |
|---|---|---|---|
| limit | integer | – | – |
| page | integer | – | – |
No output schema declared.
No examples provided.
mailercheck_verification_result Read MailerCheck email verification result ~53
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.
| Name | Type | Req | Description |
|---|---|---|---|
| verification_id | string | yes | – |
No output schema declared.
No examples provided.
mailercheck_verify_email Start MailerCheck email verification ~81
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.
| Name | Type | Req | Description |
|---|---|---|---|
| confirm | boolean | – | – |
| string | yes | – |
No output schema declared.
No examples provided.
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.
remote · mailercheck.usefulapi.io
claude mcp add --transport http io-usefulapi-mailercheck 'https://mailercheck.usefulapi.io/mcp'
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.