MCP server

WarmInboxes Free Deliverability Tools Official

com.warminboxes/deliverability-tools

Checked 25 Oct 2026, 20:29 UTC · Connected to it and listed its tools

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

Website

At a glance

Type

MCP server

Publisher

warminboxes.com (verified by the MCP Registry)

Status

Working at last check

Tools

51

Token cost

About 10,754 tokens per request

Sets up in

Claude Code, Claude Desktop, Codex, Gemini CLI, Cursor, VS Code, Antigravity, ChatGPT, OpenAI API, Grok

Last checked

25 Oct 2026, 20:29 UTC

Connect it to your agent

Add to CursorAdd to VS CodeVS Code Insiders

Opens the app, which shows the server and asks you to confirm. For other apps, copy the setup below.

Claude Code

claude mcp add --transport http deliverability-tools https://warminboxes.com/mcp

Claude Desktop

Settings → Connectors → Add custom connector, and paste the URL.

Codex (config.toml)

[mcp_servers.deliverability-tools]
url = "https://warminboxes.com/mcp"

Gemini CLI

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

Cursor

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

VS Code

{"servers":{"deliverability-tools":{"type":"http","url":"https://warminboxes.com/mcp"}}}

Antigravity

agy mcp add deliverability-tools https://warminboxes.com/mcp

ChatGPT

Settings → Apps & Connectors → Advanced settings: turn on Developer mode, then Create a connector and paste the URL. Which plans can do this varies.

OpenAI API (Responses tools)

{"type":"mcp","server_label":"deliverability-tools","server_url":"https://warminboxes.com/mcp","require_approval":"always"}

Grok (xAI API tools)

{"type":"mcp","server_label":"deliverability-tools","server_url":"https://warminboxes.com/mcp"}

Tools

• analyze_bounces ~157 tokens
  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. Separate several bounces with a blank line.
• analyze_cold_email ~211 tokens
  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 personalisation or opt-out, length. Returns each finding with ho
• analyze_dmarc_report ~232 tokens
  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, failing senders first. Takes the report XML, several of them, or
• analyze_email_html ~194 tokens
  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 loads, no pixel fires, no link is followed. The SURBL lookups
• analyze_headers ~189 tokens
  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 delays, the sending IP, plain-English issues, and whether t
• analyze_microsoft_headers ~170 tokens
  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 in Outlook junk. For Gmail or any provider's routing and ali
• audit_campaign ~328 tokens
  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 contacts per company, plus a send forecast from the sending se
• burned_inbox_guidance ~142 tokens
  Directs the person to the external Burned Inbox Checker at https://burnedinbox.com. Does not itself determine whether an inbox or domain is burned; the result gives the link and names the checks here that answer part of the question (check_domain_reputation, check_deliverability).
• check_bimi ~101 tokens
  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_blacklist ~99 tokens
  Check a domain or IP against 20+ major email blacklists (Spamhaus, Barracuda, SORBS and others) and report which list it appears on.
• check_bulk_sender_requirements ~240 tokens
  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 requirements no outside tool can see (complaint rate, per-connecti
• check_cname ~132 tokens
  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.
• check_deliverability ~142 tokens
  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" questions.
• check_dkim ~200 tokens
  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 to a provider that has not published one — the usual Microsof
• check_dmarc ~153 tokens
  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=quarantine is the step for stricter enforcement; do not tell someone
• check_dns ~116 tokens
  Query any DNS record type for a domain: MX, TXT, A, AAAA, CNAME, NS, SOA, CAA.
• check_domain_expiry ~124 tokens
  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_domain_reputation ~175 tokens
  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 what it rules out. No reputation score: receivers hold that pr
• check_email_authentication ~164 tokens
  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 when someone has been told to "fix their email authenticatio
• check_google_domain ~96 tokens
  Tell whether a domain is already attached to a Google Workspace account, or is clear for a fresh Google tenant.
• check_mta_sts ~94 tokens
  Validate a domain's _mta-sts DNS record and its published policy file: mode, MX patterns, max_age and TLS-RPT.
• check_nameservers ~115 tokens
  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_rdns ~330 tokens
  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 hostname, including one they do not own. Only the round trip is ev
• check_spf ~96 tokens
  Look up a domain's SPF record and validate it, including the recursive DNS lookup count that silently breaks SPF past 10.
• check_ssl ~254 tokens
  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 MTA-STS policy host (mta-sts.<domain>) or a click-tracking do
• check_suppression ~250 tokens
  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_surbl ~138 tokens
  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 per call.
• check_tracking_domain ~198 tokens
  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 listed tracking domain is in the body of every message, which
• clean_csv ~212 tokens
  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 the page to download the full result. Does not verify mailbox
• cold_email_writing_resources ~128 tokens
  Directs the person to Cold Email AI, the WarmInboxes cold email writing assistant at https://warminboxes.com/AI (a custom GPT on ChatGPT). Does not generate email copy itself; the result gives the link and names the tools here that check a draft (analyze_cold_email, preview_inbox, expand_spintax).
• combine_csvs ~224 tokens
  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 rows or fewer. POST JSON: files is an array.
• convert_csv ~196 tokens
  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 custom variables. Returns the mapping, and the converted CSV w
• expand_spintax ~208 tokens
  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. Use it to check a sequence before it sends.
• find_lead_lists ~256 tokens
  Searches WarmInboxes' own catalogue of about 1,000 free B2B lead lists, by industry, role and country, as published at https://warminboxes.com/leads. It does not search the web or any other database. Returns the best-matching lists with lead counts, verified email counts and each list's page. Lists
• find_resources ~310 tokens
  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 skills, the changelog, and the offer and about pages. Searches t
• find_tools ~204 tokens
  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 task to list every tool.
• generate_dns_records ~450 tokens
  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 writes records; to check what is published, use check_spf, check
• generate_unsubscribe ~235 tokens
  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.
• get_pricing ~107 tokens
  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_infrastructure.
• lookup_mx ~249 tokens
  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 others). Pass `domains` instead of `domain` for up to 100 at onc
• lookup_txt ~286 tokens
  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 — in the same lookup. Names the three mistakes that are invisi
• plan_from_list ~540 tokens
  Estimates a sending fleet for a recipient list. Looks up the MX records of up to 100 recipient domains (or addresses) to measure the Google / Microsoft / other mix, then sizes a Google Workspace pool for the Google recipients and an Azure pool (Microsoft 365 with microsoftEsp) for the Microsoft ones
• plan_infrastructure ~681 tokens
  Estimates how many inboxes and domains a daily cold email volume needs and the monthly cost at WarmInboxes' published prices. Inputs: emailsPerDay; optionally the provider (esp), prewarmed or fresh, billing cycle, emails per inbox per day and inboxes per domain. With dealValue (and optionally closeR
• plan_rotation ~224 tokens
  Suggests a two-batch inbox rotation schedule: the fleet split in half, one batch sending while the other rests, swapped every 1, 2 or 4 weeks. Returns batch sizes, the daily load per active inbox compared with a 15-a-day pace, how many inboxes the volume needs at that pace, and an eight-week calenda
• plan_verification_waterfall ~269 tokens
  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 own prices and resolve rates (POST JSON for verifiers).
• preview_inbox ~179 tokens
  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.
• quote_inboxes ~351 tokens
  Prices a given number of inboxes at WarmInboxes' published prices: the domains (or Azure tenants) they sit on, daily sending capacity at the provider's pace, monthly cost and delivery time. Use it when the person already knows the count ("preview 100 inboxes"); for a send volume use plan_infrastruct
• read_resource ~198 tokens
  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 return their data as JSON. Use the url find_resources gave yo
• segment_esp ~129 tokens
  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.
• spamhaus_dbl_guidance ~160 tokens
  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 t
• verify_email ~118 tokens
  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.

Browse

• Microsoft tools
• Website monitoring
• Domains and DNS
• Spreadsheets
• Email

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