"An email protocol for sending and receiving messages" matching MCP servers:

Enables sending transactional emails with text or HTML body, delivery status, and message ID via Resend. Pay-per-call using x402 micropayments (USDC on Base L2), no API key or signup required.

MCP server for e-commerce operations including product catalog management, cart/checkout, and Stripe integration, with built-in EU AI Act compliance.

Trust infrastructure for the machine economy. Gives AI agents non-custodial smart accounts (ERC-4337), x402 payments, on-chain reputation via ERC-8004 trust registry, and service discovery. 8 tools: create accounts, transfer, check balances, pay for x402 services, publish/discover services, manage payment agreements, and send encrypted messages.

MAP (Maraventano Agent Protocol). One MCP server with three subtractive parts — Merchant Key (read any product URL into one CleanRead), Atlas (publish your own catalog by reading yourself), Provisions (wallet curriculum), Teacher, not butler: never signs, pays, or holds keys.

Credit and payments for AI agent developers — over MCP. No crypto required

Enables AI agents to discover, query, and pay for HTTP endpoints and MCP tools using Stellar USDC/SEP-41 stablecoins through a federated P2P bazaar catalog and x402 payment facilitator.

AI payment router for routing across 300+ LLM models with per-request USDC settlement on Base and Tempo, session budgets, and x402 payments via the MCP protocol.

Pay-per-call USDC payment proxy for AI agents. Issue scoped Pay Tokens with hard spending caps and auto-journal every charge to freee / Money Forward / QuickBooks.

MCP server for Italian electronic invoicing via the Invoicetronic API, enabling management of invoices through SDI with 20 tools for sending, receiving, exporting, and more.

Provides a three-layer payment firewall for AI agents, enabling identity verification, risk screening, and execution authorization with on-chain policy enforcement for secure and auditable transactions.

Free x402 endpoint checker plus paid report and metadata tools. Remote MCP server for agents. Written by AI named Nock, not a human.

A paid MCP server that lets AI agents send SMS messages to US phone numbers via x402 micropayments, with automatic compliance and opt-out handling.

A Model Context Protocol server that exposes the pain001 ISO 20022 Customer Credit Transfer Initiation library as agent tools, enabling AI assistants to generate and validate standardized payment XML messages.

An MCP server that exposes the pacs008 ISO 20022 FI-to-FI Customer Credit Transfer library as tools for AI agents and assistants, enabling generation, validation, and parsing of pacs.008 credit transfer XML messages.

Unified gateway for ISO 20022 message families, providing meta-tools to search, describe, validate, generate, and parse financial messages.

Travel eSIMs for 193 countries. Stripe + Bitcoin checkout. QR by email in 30s. No API key.

An MCP server that lets your AI coding agent (Claude Code, OpenClaw, Codex, Cursor, etc.) discover and pay on-chain agents registered on ERC-8004, using Coinbase's official x402 protocol. No smart account. No bundler. No relay. Just your EOA, an HTTPS request, and an automatic 402 → sign → retry flow.

MCP server for the HAUL API marketplace, enabling email and phone verification, credit balance checks, and top-ups.

Pactus is an MCP server for parsing and validating ISO 20022 payment messages directly from chat. It exposes nine tools that let AI assistants inspect or validate pacs.008, pacs.002, pain.001, and camt.053 messages — the message types at the centre of the CBPR+ migration — without leaving the conversation.

Enables AI agents to analyze payment gateway error messages and receive structured triage results, including likely causes, recommended checks, and retry safety guidance.