"Email clients and services for sending, reading and managing emails outside of Gmail" 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.

Enables building client statements of account from existing invoices, credit notes, and deposits, with aged outstanding balances, PDF/plain-text output, and drafted payment chasers at friendly, firm, or final levels.

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

Enables AI agents to access DDG's payable services including checkout/payment conformance, MCP/tool security audits, agent-discovery repair, and buyer-agent smoke probes, with structured payment challenges.

Enables agents to access production-grade paid MCP tools with real on-chain x402 v2 settlement, including EVM wallet risk scoring, payload normalization, and facilitator discovery, all discoverable via Bazaar-compatible metadata.

Enables interacting with the GTA7 Lab city bank through MCP tools, including balance checks, transaction searches, PIX transfers, bill payments, card issuance, loan simulation and requests, and investments.

Read-only MCP server that performs deterministic local preflights of agent-payment boundary documents and x402 v2 PaymentRequired JSON, and prepares unsubmitted public quote-request drafts without network calls or fund movement.

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

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.

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.

Enables MCP-capable agents to search the curated gold-402 directory of x402 services, probe any endpoint for valid 402 payment terms, and optionally purchase a human editorial verdict for a resource.

Enables MCP clients to access all endpoints of an x402 gateway by paying real-time microtransactions (USDC on Base) per API call, with automatic tool discovery and spend guardrails.

Enables AI agents to discover, inspect, and pay for paid HTTP and MCP services using USDC on Solana with a self-custodial wallet.

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.

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

Enables Claude to interact with a Folio business bank account for managing accounts, transactions, receipts, bookkeeping, and payments as drafts.

Enables agents to search a verified directory of machine-payable services, inspect service and wallet reputation, and get pre-payment checks before spending.

A demo MCP server exposing billing operations (invoices, customers) with no built-in safety, designed as a test target for NitroWatch governance. It allows reading, sending, archiving, and permanently deleting accounts/invoices without confirmation.

Enables reading the school lunch calendar, managing students, placing and changing orders, and tracking deliveries and payments on a My Hot Lunchbox parent account. It signs in server-side with account credentials and exposes 38 MCP tools with confirm-gated write operations.

Enables sending letters and MICR-encoded checks, managing contacts and templates, and verifying US/Canadian addresses via the PostGrid Print & Mail and Address Verification APIs from Claude.