WarmInboxes Free Deliverability Tools
REMOTE · WARMINBOXES.COM
Free cold email deliverability checks, list tools, inbox planning and original placement research.
Available components
Last scanned (9 hours ago)
Scores higher than 58% 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 Security74
- The endpoint's TLS certificate is valid, in date, and uses a strong key. View diagnostics → Pass
- No authorisation is required to call this server. Every tool declares its destructiveHint and none is destructive, so open access doesn't expose one. See how to fix → View diagnostics → Partial
- HTTPS is enforced; there's no plaintext access path. View diagnostics → Pass
- 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 & Reachability100
- Verified streamable-http transport via a live MCP handshake. View diagnostics → Pass
Schema Quality & AI Usability69
- AI-judged instruction clarity (excellent).Pass
- Context-footprint check failed: tool/resource definitions use about 8243 tokens (~158/item across 52 items; 52 tools + 0 resources), over budget; trim descriptions and params. See how to fix → Fail
- Usage-examples check failed: none of the tools include examples. See how to fix → Fail
Stability & Change Management37
- Stability check failed: schema churn in the 13 days we've observed: 3 tool removals, 0 breaking changes, 0 auth/transport breaks, 5 additions. See how to fix → Fail
Tool Coverage100
- 100% of tools have a non-trivial description (not blank, and not just the tool's name).Pass
- 100% of tool parameters carry a description.Pass
Tool Safety75
- No prompt-injection markers were found in the server instructions, tool names or descriptions we captured.Pass
- 0 of 1 tool(s) whose name or description implies an irreversible operation declare an MCP destructiveHint annotation; "combine_csvs" implies "merge" and declares readOnlyHint instead, contradicting what its own name says it does. See how to fix → Fail
- An AI judge read all 53 captured unit(s) of tool text and found none that tries to manipulate the model reading it.Pass
Capabilities60
- Spec-recency check failed: implements MCP spec 2025-06-18; the latest is 2026-07-28. See how to fix → Fail
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.
- 4 Nov 26 +1
No change was recorded against any check on this day. Stability & Change Management went from 31 to 34.
- 2 Nov 26 +1
- The server rewrote its instructions, which are the text every model session reads security
- Tool “plan_infrastructure” rewrote its description, which is the text the model reads security
- “plan_infrastructure” added an optional parameter “currentInboxes” cosmetic
- “plan_infrastructure” added an optional parameter “reservePercent” cosmetic
- 31 Oct 26 +1
- The server rewrote its instructions, which are the text every model session reads security
- Tool “burned_inbox_guidance” rewrote its description, which is the text the model reads security
- Tool “plan_from_list” rewrote its description, which is the text the model reads security
- Tool “segment_esp” rewrote its description, which is the text the model reads security
- Server version: 1.0.0 → 1.2.0 functional
- “plan_from_list” reworded the description of “microsoftEsp” cosmetic
- Tool “burned_inbox_guidance” changed its title: Burned Inbox Checker guidance → Inbox placement test and Burned Inbox Checker cosmetic
- 28 Oct 26 +1
- The server rewrote its instructions, which are the text every model session reads security
- Tool “plan_from_list” rewrote its description, which is the text the model reads security
- Tool “quote_inboxes” rewrote its description, which is the text the model reads security
- 27 Oct 26 0
- The server rewrote its instructions, which are the text every model session reads security
- New tool “get_diagnostic_playbook” functional
- 26 Oct 26 +1
No change was recorded against any check on this day. Stability & Change Management went from 0 to 4.
- 24 Oct 26 +3
- Stability: unverified → fail ▼ security
- A breaking change shipped without a version bump: still 1.0.0 ▼ security
- Tool “check_burned_inbox” was removed ▼ security
- Tool “check_spamhaus_dbl” was removed ▼ security
- Tool “write_cold_email” was removed ▼ security
- Injection markers: fail → pass ▲ security
- The server rewrote its instructions, which are the text every model session reads security
- Tool “find_lead_lists” rewrote its description, which is the text the model reads security
- Tool “plan_from_list” rewrote its description, which is the text the model reads security
- Tool “plan_infrastructure” rewrote its description, which is the text the model reads security
- Tool “plan_rotation” rewrote its description, which is the text the model reads security
- New tool “burned_inbox_guidance” functional
- New tool “cold_email_writing_resources” functional
- New tool “quote_inboxes” functional
- New tool “spamhaus_dbl_guidance” functional
- “plan_infrastructure” reworded the description of “prewarmed” cosmetic
- Tool “find_lead_lists” changed its title: Free B2B lead lists → Free B2B lead lists (WarmInboxes catalogue) cosmetic
- Tool “plan_from_list” changed its title: Fleet plan from a recipient list → Fleet estimate from a recipient list cosmetic
- Tool “plan_infrastructure” changed its title: Inboxes and domains for a send volume → Inboxes and domains for a send volume (estimate) cosmetic
- Tool “plan_rotation” changed its title: Inbox rotation plan → Inbox rotation schedule (suggested) cosmetic
- 23 Oct 26 64
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://warminboxes.com/mcp
TLS valid
Negotiated TLS 1.3 with TLS_AES_128_GCM_SHA256 .
| Subject | Issuer | Valid from | Valid until | Key | Signature | Serial |
|---|---|---|---|---|---|---|
| CN=warminboxes.com | CN=WE1,O=Google Trust Services,C=US | 26 Sept 2026 | 25 Dec 2026 | ECDSA 256 | ECDSA-SHA256 | 21e4b3c7c23b521f0e296a3b32f35222 |
| SANs: warminboxes.com, *.warminboxes.com | ||||||
| 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 warminboxes.com. — Not signed
| Zone | DS | Keys | Algorithms | Outcome |
|---|---|---|---|---|
| . | trust_anchor | 20326, 38696 | 8, 8 | Verified |
| com. | present | 19718 | 13 | Verified |
| warminboxes.com. | absent | Unsigned (proven) parent-signed NSEC/NSEC3 proves an unsigned delegation |
Authentication No authorisation required
The endpoint answered without asking for a token. Anyone who knows the URL can reach it.
| Result | No authorisation required |
|---|---|
| HTTP status | 200 |
Background: How OAuth 2.1 works in the 2026 MCP spec →
Transports 2 probes
| Transport | URL | Outcome | Status | Location |
|---|---|---|---|---|
| streamable-http | https://warminboxes.com/mcp | Verified | 200 | |
| http (plaintext) | http://warminboxes.com/mcp | HTTPS enforced | 301 | https://warminboxes.com/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 →
spamhaus_dbl_guidance Spamhaus DBL guidance (not queried) ~104
Explains how to check a domain on the Spamhaus Domain Block List by hand at https://check.spamhaus.org. Does not query the Spamhaus DBL (it needs a paid key) and never returns a listing verdict: the result states that nothing was checked, gives Spamhaus's own lookup, and names the blocklist checks this server does run (check_surbl, check_blacklist).
| Name | Type | Req | Description |
|---|---|---|---|
| domain | string | – | The domain asked about. |
No output schema declared.
No examples provided.
verify_email Email verification (bulk) ~55
Check email addresses for syntax, live MX records, disposable providers and role prefixes (info@, sales@). Does not open SMTP connections, so catch-all domains come back valid.
| Name | Type | Req | Description |
|---|---|---|---|
| emails | array | yes | Email addresses to verify. |
No output schema declared.
No examples provided.
How do I install the WarmInboxes Free Deliverability Tools MCP server?
WarmInboxes Free Deliverability Tools is a hosted endpoint at https://warminboxes.com/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 · warminboxes.com
claude mcp add --transport http com-warminboxes-deliverability-tools 'https://warminboxes.com/mcp'
What is the WarmInboxes Free Deliverability Tools MCP server?
WarmInboxes Free Deliverability Tools is an MCP server listed in the public MCP registry as com.warminboxes/deliverability-tools. Free cold email deliverability checks, list tools, inbox planning and original placement research. This page covers its hosted endpoint (https://warminboxes.com/mcp).
Is the WarmInboxes Free Deliverability Tools MCP server safe to use?
WarmInboxes Free Deliverability Tools scores 72 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 WarmInboxes Free Deliverability Tools MCP server expose?
WarmInboxes Free Deliverability Tools exposes 52 tools: check_deliverability, check_spf, check_dkim, check_dmarc, check_bimi, and 47 more. Their descriptions and schemas cost roughly 7,169 tokens of context every time the server is loaded.
Does the WarmInboxes Free Deliverability Tools MCP server require authentication?
No. We connected to WarmInboxes Free Deliverability Tools without credentials and it answered, so anything it exposes is reachable by anyone who knows the address.
Is the WarmInboxes Free Deliverability Tools MCP server still maintained?
WarmInboxes Free Deliverability Tools 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.