Warminboxes.com MCP server

• Registry namecom.warminboxes/deliverability-toolsverified in the MCP registry

The registry name sits under warminboxes.com. The registry only lets a publisher use that namespace after proving control of the domain through DNS or HTTP.

• Stateanswerschecked 2026-10-22
• Tools50
• Server calls itselfwarminboxes-deliverability-tools
• Server version1.0.0
• Protocol version2025-06-18

On 2026-10-22 the server answered initialize and tools/list without a sign-in. First answer in 164 ms.

• Its tools do none of the product's use cases we checked: Launch cold email sending on prewarmed inboxes without a warmup wait; Add fresh inboxes on your own domains to increase sending volume.
• Checked on 3 of the 7 days it takes to judge reliability.

Said by rules from the measurements above. The likely first call is a model's pick from the tool list; read its description before relying on it.

• INITE MCP scoreafter a weeka score needs 7 daily checks: 3 so far
• What an agent can do with it0 of 2 use cases
• Answeredmeasuring3 of the 7 daily checks it takes to print a share
• Median first answer399 ms
• Space in an agent's context≈ 9,405 tokensthe definitions of all its tools (51), which an agent carries on every turn
• Tool definitionsA · 100 of 100
• Typed results0 of 51 toolsdeclared outputSchema: results come typed, read once

• Every tool passes all six checks.

A program checks the server once a day: initialize and tools/list, no model. Tokens are the definitions' length at about four characters a token. The grade averages six checks of every tool's name, description, schema and annotations; it says how well the tools are described, not whether they work. The score weighs what was measured and nothing else: answering (30%), doing the product's job (25%), definitions (20%), context (10%) and use (15%). A part that was not measured is left out, and a hidden instruction caps the score at 40. The state of vendors' MCP servers: method and numbers →

• 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"…

• 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…

• 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…

• 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…

• 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…

• 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…

• 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…

• 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…

• 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…

• 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…

• 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…

• 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…

• 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…

• 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…

• 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…

• 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…

• 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…

• 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…

• 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…

• 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…

• 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…

• 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…

• 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…

• 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…

• 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…

• 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…

• 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_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…

• 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…

• 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…

• 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…

• 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…

• 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…

• 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…