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WarmInboxes Free Deliverability Tools

MCP server · hosted · v1.0.0 · com.warminboxes/deliverability-tools
Online · tested 2h agoNEW · 3h agoSeen in the registry 2h ago

Free cold email deliverability checks, list tools, inbox planning and original placement research.

Website ↗How to connect ↓

What it does

WarmInboxes Free Deliverability Tools is an MCP server, a connector that lets an AI assistant use it as a tool. It is hosted: an assistant connects to it over the internet, nothing to install.

From the publisher's description, Electra Index matched it to one capability: outreach sequencing. That makes it a candidate for tasks such as recruit developers or send personalized outreach.

Facts come from the Official MCP Registry, as declared by the publisher. Capabilities are matched automatically (low confidence) and are not a test of the tool.

At a glance

Hosted (remote)YES
Local installNO
Version1.0.0
PriceNot in the registry
First seen22 Oct 2026
Last checked2h ago

How to connect

As declared in the Official MCP Registry · hosted endpoint tested by Electra Index 2h ago (live check)

Hosted endpoint

  • https://warminboxes.com/mcp streamable-http

In Claude Code: claude mcp add --transport http warminboxes-free-deliverability-tools https://warminboxes.com/mcp

MCP settings (Claude Desktop, Cursor and other MCP clients)

{
  "mcpServers": {
    "warminboxes-free-deliverability-tools": {
      "url": "https://warminboxes.com/mcp"
    }
  }
}

Live check

Electra Index connected to the hosted endpoint 2h ago

ONLINE WarmInboxes Free Deliverability Tools answered an MCP connection on 22 Oct 2026 and introduced itself as warminboxes-deliverability-tools 1.0.0 (MCP protocol 2025-06-18).

50 tools offered to AI assistants

  • check_deliverability · Grade a domain A-F for cold email readiness. Checks SPF, DKIM, DMARC, MX, blacklists and domain age together and returns a weighted score with a per-check breakdown and what to fix. Start here for open-ended "is this domain any good" questi
  • check_spf · Look up a domain's SPF record and validate it, including the recursive DNS lookup count that silently breaks SPF past 10.
  • check_dkim · Find and validate a domain's DKIM signing key, including key strength. Leave selector empty to auto-scan 26 common selectors (google, selector1, k1, and the rest). When no key is found, reports whether the selectors are delegated by CNAME t
  • check_dmarc · Look up and parse a domain's DMARC record: policy, subdomain policy, percentage, alignment and reporting tags, each explained. p=none (monitoring) passes: it meets Google and Yahoo's requirement and is fine for broad cold email. p=quarantin
  • check_bimi · Validate a domain's BIMI record, the logo SVG, the VMC, and the DMARC enforcement level Gmail requires before it will show a brand logo.
  • check_mta_sts · Validate a domain's _mta-sts DNS record and its published policy file: mode, MX patterns, max_age and TLS-RPT.
  • check_ssl · Read a host's TLS certificate: issuer, validity dates and days remaining, subject alternative names, key type and size, signature algorithm, chain, negotiated protocol and whether the chain is trusted and covers the hostname. Use it on an M
  • check_dns · Query any DNS record type for a domain: MX, TXT, A, AAAA, CNAME, NS, SOA, CAA.
  • lookup_txt · Every TXT record on a domain, with each one identified (SPF, DKIM, DMARC, MTA-STS, TLS-RPT, BIMI, or which service's ownership token it is), plus the four underscore names a receiver reads — _dmarc, _mta-sts, _smtp._tls and default._bimi —
  • check_rdns · The PTR record for an IPv4 or IPv6 address, and the forward lookup that decides whether it counts. Reverse DNS is delegated to whoever holds the address block, so a PTR alone proves nothing — the operator of an IP can point it at any hostna
  • check_blacklist · Check a domain or IP against 20+ major email blacklists (Spamhaus, Barracuda, SORBS and others) and report which list it appears on.
  • check_surbl · Check domains against the SURBL URI blacklist in bulk. URI blacklists list the domains that appear inside a message body, so a listed tracking or landing domain sends the whole email to spam however clean the sender is. Up to 100 domains pe
Show 38 more
  • check_nameservers · Get the NS records and the DNS provider behind one domain or a whole list. Useful for working out who actually controls a domain's DNS before trying to fix its records.
  • check_domain_expiry · Get a domain's registrar, creation date, expiry date and days remaining, over RDAP with a WHOIS fallback for ccTLDs that publish no RDAP service. Domain age is one of the strongest cold-email risk signals.
  • check_google_domain · Tell whether a domain is already attached to a Google Workspace account, or is clear for a fresh Google tenant.
  • check_cname · Follow a host's full CNAME chain and flag the mistakes that break a cold-email tracking domain. Pass expected to assert where the chain should end up.
  • verify_email · 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.
  • lookup_mx · Look up a domain's MX records with priorities and resolved IPs, and identify the mailbox provider (Google Workspace, Microsoft 365, Zoho, Fastmail and others) and any security gateway in front of it (Mimecast, Proofpoint, Barracuda and othe
  • segment_esp · Split a list of domains by the email provider behind them (Google, Microsoft, or a security gateway) from their MX records. Sending Google-to-Google and Microsoft-to-Microsoft is one of the larger levers on inbox placement.
  • plan_from_list · From a list of recipient domains (or addresses) and a daily sending target to a costed, split fleet in one call: the Google/Microsoft/unmatched mix of the list, a Google Workspace pool for the Google recipients, an Azure pool for the Micros
  • plan_infrastructure · Work out how many inboxes and domains a daily cold email volume needs, and what it costs per month. Use this for "how many inboxes do I need for N a day". Give dealValue to get the revenue and ROI math as well.
  • expand_spintax · Expand a spintax template such as "{Hi|Hey} there" and render its Liquid merge tags, returning the total number of variations, every variable the template references, any variable with no value and no default, and a set of rendered samples.
  • generate_unsubscribe · Build a CAN-SPAM and GDPR compliant opt-out footer in plain text and HTML, with a checklist saying which compliance requirements the details given actually satisfy. A footer with no postal address is the usual failure.
  • check_email_authentication · SPF, DKIM, DMARC, MX, BIMI and MTA-STS for one domain in one call, each judged pass, weak, fail or not set, with the essentials separated from the optional records. BIMI and MTA-STS are optional and come back "absent", never failed. Use it
  • check_domain_reputation · For "this domain used to land and now it does not". Checks the domain against SURBL, its authentication, its age and the address its website resolves to, and returns a verdict by elimination (listed, broken, young, clean or unknown) with wh
  • check_tracking_domain · Check the domain a campaign's tracked links point at: whether it resolves, serves a valid certificate, is listed on SURBL, sits on a listed address, belongs under the sending domain, and whether it is a platform's shared tracking host. A li
  • check_bulk_sender_requirements · The bulk sender requirements, sorted honestly: SPF, DKIM, DMARC and MX checked from DNS; forward and reverse DNS when given the sending IP; one-click unsubscribe and From alignment when given a received message's raw headers; and the requir
  • analyze_headers · Read a received message's raw headers. Returns the SPF, DKIM and DMARC verdicts the receiver recorded, which domains authenticated and whether they align with the From domain (why DMARC failed on a message that "passed"), the relay hops and
  • analyze_email_html · Read an email's HTML. Returns its size against Gmail's ~102 KB clipping limit with what is taking the room, every link and image host, tracking pixels, URL shorteners, and each linked domain checked against SURBL. Parsed inertly: nothing lo
  • analyze_dmarc_report · Read DMARC aggregate (rua) reports and say who is sending as the domain and what fails: messages passing and failing, failures that are alignment only, quarantined and rejected counts, and each sending IP with its SPF and DKIM outcome, fail
  • analyze_cold_email · Score a cold email's copy 0-100 for spam risk before it is sent: weighted trigger words by category and severity (subject hits weigh extra), ALL-CAPS, links and shorteners, currency and percent-off offers, obfuscated spellings, missing pers
  • audit_campaign · Audit a cold email campaign before launch: the lead CSV and the sequence checked together for merge tags with no column or empty values, variable syntax the sequencer will not parse, role and disposable addresses, duplicates and too many co
  • analyze_bounces · Classify bounce messages (NDRs): invalid address, full or disabled mailbox, reputation block, authentication failure, throttling, content block or configuration, each with whether it is hard, soft or a block, why it happened and what to do.
  • analyze_microsoft_headers · Read the spam verdict Microsoft 365 or Outlook stamped on a delivered message: SCL (spam confidence), BCL (bulk), PCL, SFV, the category, and the SPF, DKIM, DMARC and composite authentication results, each explained. Use it when mail lands
  • preview_inbox · Show how a cold email's sender name, subject line and preview text are cut off in Gmail desktop, Gmail mobile and Outlook, with warnings (no sender name, all caps, empty preview, etc.). Use it to check a subject line fits before sending.
  • generate_dns_records · Write an SPF record from the providers that send for a domain (with an estimate of its DNS lookups against the limit of 10), a DMARC record from a policy, and where a provider publishes DKIM. Returns host, type and value to publish. It writ
  • plan_rotation · Plan a two-batch inbox rotation: the fleet split in half, one batch sending while the other rests, swapped every 1, 2 or 4 weeks. Returns batch sizes, the per-inbox daily load on the active batch against the 15/day house pace, how many inbo
  • plan_verification_waterfall · Price an email verification waterfall: the list run through verifiers in sequence with unknowns passed down the chain, every order compared, cheapest cost per usable email first. Uses typical figures for three verifiers unless you pass your
  • clean_csv · Clean a lead CSV: malformed, duplicate, role-based (info@, sales@) and disposable addresses removed, with a count for each reason. Returns the cleaned CSV when it is 500 rows or fewer; a larger file is summarised and the person is sent to t
  • convert_csv · Rename a lead CSV's columns to the fields a sequencer imports (Instantly, Smartlead, EmailBison, or generic snake_case). Every row and column is kept; only the header changes, and columns with no standard field keep a snake_case name for cu
  • combine_csvs · Merge several lead CSVs into one, matching columns that mean the same thing (Email, email_address, E-mail), optionally removing duplicate emails and adding a column for the file each row came from. Returns the combined CSV when it is 500 ro
  • check_suppression · Check a campaign list against a do-not-contact list before sending: exact email matches and, optionally, whole suppressed domains, with a per-company cap. Returns what was removed and why, and the clean CSV when it is 500 rows or fewer.
  • check_spamhaus_dbl · The Spamhaus Domain Block List needs a paid query key and is NOT queried by this server. Call this when someone asks about Spamhaus: it says plainly that nothing was checked, names the blocklists that do run here (check_surbl, check_blackli
  • check_burned_inbox · The Burned Inbox Checker runs on its own free site, burnedinbox.com, not on this server. Call it when someone asks whether a domain or inbox is burned: it sends them there and names the checks here that answer part of the question (check_do
  • write_cold_email · Cold Email AI, WarmInboxes' free custom GPT for writing cold email copy, runs on ChatGPT at warminboxes.com/AI, not on this server. Call it when someone wants help writing cold emails: it sends them there and names the checks here for a dra
  • find_lead_lists · Search the WarmInboxes free leads database (about 1,000 B2B lead lists by industry, role and country) and return the best matches with lead counts, verified email counts and each list's page. For questions about finding leads or a prospect
  • find_tools · Find the WarmInboxes free tool for a task ("check my email headers", "clean a CSV", "will this land in spam") and say how to use it: the MCP tool to call here, or the page to send the person to when it runs only in the browser. Call with no
  • find_resources · Search what WarmInboxes publishes: cold email guides, deliverability playbooks, original studies and their datasets, costed infrastructure recipes, tool demo videos, inbox guides per sequencer and AI agent, provider comparisons, Claude skil
  • read_resource · Read a WarmInboxes guide, study, playbook, dataset, recipe, comparison or changelog entry in full, as markdown. Long pages come in parts split at headings: the first call says how many, and nextPart gives the one to ask for. Datasets also r
  • get_pricing · The WarmInboxes price list as data: prewarmed and fresh inboxes on Google Workspace, Microsoft 365 and Azure, every billing cycle, the safe daily send pace per inbox, and delivery time. For a costed fleet for a volume, use plan_infrastructu

What "online" means: the server answered an MCP connection at the time of the check. It is not a guarantee of security, quality or continuous uptime. How we test: we open an MCP session and ask for the tool list, as an AI assistant would. We never run a tool and never send a key. Checked every few days. Method

Is this your server? Monitoring Pro: a check every 30 minutes and an email within the hour when it stops answering. $9.99/month.

Tasks it helps with

Share of each task's required capabilities it covers
Recruit developers
Outreach Sequencing
33%
Send personalized outreach
Outreach Sequencing
33%

Similar tools

Listed for the same task: recruit developers

Ready-made AI agents

An MCP server is a connector you add to your own assistant. These are finished products that do the same job for you:

Facts & evidence

Each fact shows where it was seen and when.
FactValueEvidenceSourceLast confirmed
Hosted endpointhttps://warminboxes.com/mcpDECLAREDSRC-001 Official MCP Registry2h ago
Local install (package)noDECLAREDSRC-001 Official MCP Registry2h ago
Remote access (hosted)yesDECLAREDSRC-001 Official MCP Registry2h ago
Websitehttps://warminboxes.com/for-aiDECLAREDSRC-001 Official MCP Registry2h ago
Registry statusactiveDECLAREDSRC-001 Official MCP Registry2h ago
Version1.0.0DECLAREDSRC-001 Official MCP Registry2h ago
MCP serveryesDECLAREDSRC-001 Official MCP Registry2h ago

Change history

  • NEW22 Oct 2026
    first seen in the index

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Questions about WarmInboxes Free Deliverability Tools

How do I connect WarmInboxes Free Deliverability Tools?

Use the hosted endpoint https://warminboxes.com/mcp in your assistant's MCP settings. The exact settings are in "How to connect" above, as declared in the Official MCP Registry.

What tools does WarmInboxes Free Deliverability Tools offer?

When Electra Index connected on 22 Oct 2026, it listed 50 tools: check_deliverability, check_spf, check_dkim, check_dmarc, check_bimi, check_mta_sts, check_ssl, check_dns and more. The full list is in "Live check" above.

Is WarmInboxes Free Deliverability Tools online?

Yes. Its hosted endpoint answered an MCP connection from Electra Index 2h ago.

What can I use WarmInboxes Free Deliverability Tools for?

Based on its description, it is most relevant to: recruit developers, send personalized outreach.