Postio — UK Address, Postcode, Email & Phone Validation

Name: Postio — UK Address, Postcode, Email & Phone Validation
Author: postio-uk

by postio-ukversion 0.1.5i★ –iRuns on your computer

Registry nameuk.co.postio/postcode-address-validation

Install

Overview

Description from the maker (original English)

Validate UK addresses, postcodes, emails and phone numbers — Royal Mail PAF, live SMTP and HLR.

PopNx MCP’s three pillars

These three are never merged into one score: opinions, measurements and popularity are different things.

User voiceiNo reviews yetReviews open together with accounts in a later step
Our basic checksi1 of 1 passedChecked from public information; code not scanned yet
UsageiNot measured yet★ –

What you can do with it

We have not written a plain-language summary for this one yet. Below are the facts we read from the registry.

Connection: Runs on your computer
Transport: stdio
Category: Chat & email
You need to fill in: POSTIO_API_KEY

Install

Pick the AI app you use, then copy the settings.

Before you install

Basic checks: 1 of 1 passed
Runs on your computer with your user’s permissions (files, network, apps).
You fill in yourself: POSTIO_API_KEY, POSTIO_BASE_URL

Values marked secret are keys to your account. Never share them or paste them into a chat.

You need

npmNode.js installed (for the npx command)

Which app do you use?

ClaudeClaude CodeCursorVS CodeChatGPT

Pick your app above. We remember it, so next time the button says “Install in …”.

Open Claude Desktop → Settings → Developer → Edit Config, and paste this into claude_desktop_config.json

{
  "mcpServers": {
    "postcode-address-validation": {
      "command": "npx",
      "args": [
        "-y",
        "@postio/mcp"
      ],
      "env": {
        "POSTIO_API_KEY": "your-value",
        "POSTIO_BASE_URL": "your-value"
      }
    }
  }
}

Run this in your terminal

claude mcp add postcode-address-validation --env POSTIO_API_KEY=your-value --env POSTIO_BASE_URL=your-value -- npx -y @postio/mcp

Fill in the empty values before running it.

Open in Cursor

Or copy the settings yourself

Paste into .cursor/mcp.json in your project, or ~/.cursor/mcp.json

{
  "mcpServers": {
    "postcode-address-validation": {
      "command": "npx",
      "args": [
        "-y",
        "@postio/mcp"
      ],
      "env": {
        "POSTIO_API_KEY": "your-value",
        "POSTIO_BASE_URL": "your-value"
      }
    }
  }
}

Your browser asks to open the app, then the app shows the settings and asks you to confirm. Key values are left empty for you to fill in.

Open in VS Code

Or copy the settings yourself

Paste into .vscode/mcp.json in your project

{
  "servers": {
    "postcode-address-validation": {
      "type": "stdio",
      "command": "npx",
      "args": [
        "-y",
        "@postio/mcp"
      ],
      "env": {
        "POSTIO_API_KEY": "your-value",
        "POSTIO_BASE_URL": "your-value"
      }
    }
  }
}

Your browser asks to open the app, then the app shows the settings and asks you to confirm. Key values are left empty for you to fill in.

This one runs on your computer, and ChatGPT can only connect to servers on the internet. Pick another app.

Your choice stays on this device in a cookie; no account needed.

Values you fill in

POSTIO_API_KEY secret required env
Postio API key (pk_…). Free key, first 100 lookups on us, no card: https://postio.co.uk/signup
POSTIO_BASE_URL env
Override the API base URL. Defaults to https://api.postio.co.uk/v1 (include /v1). Only needed for staging.

These settings are generated from the maker’s registry entry. If the README says otherwise, follow the README.

What it can do

Runs on your computer; the tool list appears in your AI app after you install it.

Basic checksi

We check information anyone can see; we have not read the code. Checks that do not apply are left out of the count. · Checked Nov 7, 2026

✓ Pass
Maker matches the repo
The registry name was verified against the domain postio.co.uk (the registry checks domain ownership)
… Not checked yet
Still maintained
We have not read this repo from GitHub yet
… Not checked yet
Has a licence
We have not read this repo from GitHub yet
– Not applicable
Endpoint responds
This one runs on your computer; there is no internet endpoint
– Not applicable
Sign-in with OAuth
Runs on your computer and uses local settings instead
… Not checked yet
No hidden instructions in tool descriptions
Runs on your computer; we can only read tool lists from internet endpoints

Compared with others in Chat & emaili

More stars than 0% of the other 1777 servers in this category
Published to the registry more recently than 66% of the other 1777 servers in this category
Basic checks equal to or better than 100% of the other 1777 servers in this category

Compared with every active server in this category in the registry. Stars count only when the publisher owns the repo.

Common questions

Is Postio — UK Address, Postcode, Email & Phone Validation safe?

It passed 1 of 1 applicable basic checks. We have not read the code. Before adding a key or token, see what access the server asks for and use a key with only the permissions you need.

What keys or codes does it need?

You need to fill in: POSTIO_API_KEY

Does it run on my computer or in the cloud?

It runs on your computer. Your AI app starts it when needed, and data does not pass through the maker’s servers (unless it calls an online service itself).

Is it still maintained?

The GitHub repo last changed –, and the latest version (0.1.5) reached the registry 14 days ago.

Which apps can use it?

Apps that support MCP, such as Claude Desktop, Claude Code, Cursor and VS Code. You also need Node.js on your computer.

What can I use instead?

In the same category: Vexa, emailmd, MCP WhatsApp Cloud

Alternatives

Servers in the same category from other makers, sorted by stars.

Reading a card:★ GitHub starsiThree pillars: reviews · checks · usageiUpdated = latest version published to the registryi

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emailmd

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Render markdown into email-safe HTML, lint drafts for deliverability problems, and preview emails.

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MCP WhatsApp Cloud

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Install

README from the maker

Open the README

Copied from the maker’s repo as written. PopNx MCP has not reviewed or endorsed it. HTML, images and scripts are removed. Links lead off this site.

@postio/mcp

Model Context Protocol server for Postio — the UK validation API for addresses, emails and phone numbers, exposed as tools for any MCP-aware AI host.

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

Works with Claude Desktop, Claude Code, Cursor, Windsurf, Zed, Continue, and anything else that speaks MCP over stdio.

Node 20+.

Install

You don't, really. Use npx from your host's MCP config.

Claude Code

claude mcp add postio --env POSTIO_API_KEY=pk_… -- npx -y @postio/mcp

Claude Desktop

Edit ~/Library/Application Support/Claude/claude_desktop_config.json (macOS) or %APPDATA%\Claude\claude_desktop_config.json (Windows):

"mcpServers": { "postio": { "command": "npx", "args": ["-y", "@postio/mcp"], "env": { "POSTIO_API_KEY": "pk_…" } } } }

Cursor

~/.cursor/mcp.json (or /.cursor/mcp.json for project-scoped):

"mcpServers": { "postio": { "command": "npx", "args": ["-y", "@postio/mcp"], "env": { "POSTIO_API_KEY": "pk_…" } } } }

Windsurf / Zed / Continue

Same JSON as Cursor — they all consume the standard MCP server config shape.

Tools

Tool	What it does	Billable
`postio_address_search`	Free-form UK address search → suggestions + UDPRNs	No
`postio_postcode_lookup`	All PAF delivery points at a postcode	Yes (on hit)
`postio_udprn_lookup`	Full record for a single UDPRN	Yes (on hit)
`postio_email_validate`	Syntax + typo + MX + SMTP + classification	Yes
`postio_phone_validate`	Parse + live HLR lookup (carrier, ported, reachable)	Yes
`postio_connect`	Free health probe	No

The tools are intentionally primitive and 1:1 with the API. The agent decides when to chain them — a typical address-finder flow is postio_address_search → pick a UDPRN → postio_udprn_lookup for the full record.

Each tool returns the raw API envelope as JSON text, including meta.requestId for support correlation.

Example prompts

"Look up the address with udprn 25742215."

→ postio_udprn_lookup with udprn=25742215

"Find addresses on Wimpole Street W1G."

→ postio_address_search with query="Wimpole Street W1G"

"Is alice@gnail.com a real email address?"

→ postio_email_validate with email="alice@gnail.com" →

the response includes didYouMean: "gmail.com".

"Verify these UK phone numbers and tell me which are mobile."

→ postio_phone_validate per number.

Configuration

Env var	Purpose
`POSTIO_API_KEY`	Required. Your Postio API key.
`POSTIO_BASE_URL`	Optional override of the API base URL (default `https://api.postio.co.uk/v1`).

A missing POSTIO_API_KEY is not fatal — the server still starts and advertises its tools, so a host can list them before you've configured credentials. Individual calls then fail with a message telling you to set the key.

Official MCP Registry

Listed at registry.modelcontextprotocol.io as `uk.co.postio/postcode-address-validation`, published under a domain-verified namespace (not a personal GitHub one).

curl "https://registry.modelcontextprotocol.io/v0.1/servers/uk.co.postio%2Fpostcode-address-validation/versions/latest"

The listing is generated from server.json in this directory; the version there tracks this package's version. CI (publish-mcp-registry.yml) republishes on change.

License

MIT.

Postio — UK Address, Postcode, Email & Phone Validation

Overview

PopNx MCP’s three pillars

What you can do with it

Install

Before you install

Values you fill in

What it can do

Basic checksi

Maker matches the repo

Still maintained

Has a licence

Endpoint responds

Sign-in with OAuth

No hidden instructions in tool descriptions

Compared with others in Chat & emaili

Common questions

Alternatives

Vexa

emailmd

MCP WhatsApp Cloud

README from the maker

@postio/mcp

Install

Claude Code

Claude Desktop

Cursor

Windsurf / Zed / Continue

Tools

Example prompts

Configuration

Official MCP Registry

License