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Postio — UK Address, Postcode, Email & Phone Validation MCP server

by postio.co.uk·uk.co.postio/postcode-address-validation·v0.1.5
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Validate UK addresses, postcodes, emails and phone numbers — Royal Mail PAF, live SMTP and HLR.

B80/100grade B
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Safety scan
B80/100

full report

Adoption
Growing

0 stars93 downloads/wk

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Postio — UK Address, Postcode, Email & Phone Validation tools (6, 1 write)

write = sends, deletes, buys or posts

Read from the package source without running it. The installed server may list more.

  • postio_address_search

    Search UK addresses by free-form text — building, street, postcode, organisation, or any combination. Returns a list of suggestions, each with a UDPRN (Royal Mail's per-address ID). Pass a chosen UDPRN to `postio_udprn_lookup` to fetch the full record. Free / non-billable.

  • postio_connect

    Free key/health probe. Returns 200 if the API key is active and the upstream search service is reachable. Useful as a smoke test or to warm the worker.

  • postio_email_validatewrite action

    Validate an email address: syntax (RFC 5322), typo correction (gnail→gmail), classification (disposable, role, free provider), MX lookup, and live SMTP mailbox probe. Returns an aggregated `deliverability` verdict (deliverable / undeliverable / risky / unknown / invalid) plus every signal independently.

  • postio_phone_validate

    Parse a phone number with libphonenumber and run a live HLR (Home Location Register) lookup. Returns current carrier (post-porting), original carrier, ported flag, reachability, MCC/MNC. Pass numbers in E.164 (`+447700900123`) for unambiguous results.

  • postio_postcode_lookup

    Return every PAF delivery point at a UK postcode, ordered by building number. Whitespace and case are normalised. Billable on a hit; valid postcodes with no delivery points return an empty list and are not charged.

  • postio_udprn_lookup

    Look up a single UK delivery point by its UDPRN (Royal Mail's stable per-address ID). Use this after `postio_address_search` to fetch the full record for a chosen suggestion. Billable on a hit; misses (404) are not charged.

Public scan report

scanner v0.1.10 · 2026-11-03 · same rubric, same numbers if you re-run it

no findings
  • Code scan3 source files scanned25/25
  • –Live reliabilityno gateway calls yet and no remote to proben/a
  • –Tool poisoningtools not inspected (local package is not executed); not countedn/a
  • Auth qualitystatic API keys via environment variables6/15
  • Maintenancelast push 11 days ago15/15
  • Maintainer identitynamespace and repository owner differ; website matches verified namespace6/10
Overall 80/100. Components that don't apply are left out of the denominator. Any critical finding is an F.RubricAppeal a findingJSON

How Postio — UK Address, Postcode, Email & Phone Validation compares

Against every graded Email MCP server, from our own scans and uptime checks. Updated after each scan run.

Safety score
80/100
higher than 65% of 916 Email servers
Tools
6
the typical Email server has 7
Tools that change things
17%
typical: 25%. Fewer write tools means less an agent can break
Downloads a week
93
more than 58% of 235 Email servers with a package

What its tools let an agent do: 6 send or post

Release history: 2 versions in the registry since 2026-08-14, latest 2026-10-23, typically one every 70 days.

Install Postio — UK Address, Postcode, Email & Phone Validation in Claude Code, Cursor or VS Code

Runs npx -y @postio/mcp on your machine. Read the scan report first; the gateway never runs local packages.

claude mcp add postcode-address-validation -- npx -y @postio/mcp
Add to Cursor

What the publisher says

From the Postio — UK Address, Postcode, Email & Phone Validation repository's README, as published. We do not edit it. Read it on GitHub

postio-integrations

Postio is the UK validation API for addresses, emails and phone numbers. This repo holds the JS-family npm packages, the AI / agent surface, and the cdn.postio.co.uk Worker that powers Postio's browser drop-in.

First time? Sign up free — first 100 lookups on us, no card needed.

The Postio API + OpenAPI spec live in postio-uk/postio-api. The spec is also published as @postio/openapi.

Packages

Layout

packages/         pnpm workspace; one publishable npm package per subdir
ai/               AI / agent surface (Claude Skill, GPT Action, recommendation prompts)
cdn-worker/       Cloudflare Worker that serves the address-finder bundles
.github/workflows/  CI for publishing + deploying

Building

cd packages
pnpm install
pnpm -r run build

Each package builds independently (pnpm -F @postio/ run build). The address-finder bundle has a topological-build quirk — use the ... suffix so its workspace dep builds first:

pnpm -F "@postio/address-finder-bundled..." run build

Contributing

PRs welcome. Conventions:

in package.json when you intend a release.

  • Node 22+, pnpm 10+, ESM only, MIT-licensed.
  • stage is the working branch; master deploys / publishes via CI.
  • One package change per PR where possible.
  • Versions on each package are independent SemVer; bump the version

The full integration index — including the server SDKs in their own repos and the WordPress plugin — lives at postio.co.uk/integrations.

License

MIT.

Nothing above is checked by us. What we check is on the safety report.

Postio — UK Address, Postcode, Email & Phone Validation: common questions

Is Postio — UK Address, Postcode, Email & Phone Validation MCP server safe?
Mostly: it is graded B (80/100). Read the Postio — UK Address, Postcode, Email & Phone Validation safety report
How do I install Postio — UK Address, Postcode, Email & Phone Validation?
It runs on your machine. Copy the Claude Code, Cursor, VS Code or Claude Desktop config from the install section.
Does Postio — UK Address, Postcode, Email & Phone Validation need an API key?
Yes. The registry entry asks for POSTIO_API_KEY.
Is Postio — UK Address, Postcode, Email & Phone Validation maintained?
The last commit was 12 days ago (2026-10-23). The latest release is v0.1.5.
What can I use instead of Postio — UK Address, Postcode, Email & Phone Validation?
Servers from other publishers that do the same job: Proton Mail (unofficial) MCP server, Postfleet MCP server and Mailoo - Email MCP Server. Compare all Postio — UK Address, Postcode, Email & Phone Validation alternatives.
How does Postio — UK Address, Postcode, Email & Phone Validation compare with other Email MCP servers?
safety score 80/100 (higher than 65% of 916 Email servers); tools 6 (the typical Email server has 7); tools that change things 17% (typical: 25%. Fewer write tools means less an agent can break). Full comparison.

Alternatives to Postio — UK Address, Postcode, Email & Phone Validation

Same job from other publishers: the closest match first, then the best rated.

All Postio — UK Address, Postcode, Email & Phone Validation alternatives →
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