"Proton Mail" matching MCP connectors:

Print & mail PDF/HTML/Markdown/text/DOCX/images to US addresses; pay per call in x402 USDC on Base.

Print and mail physical letters and postcards to US postal addresses, plus address verification. Upload PDF/HTML/Markdown/text/DOCX/image documents, get a quote, and pay per call with x402 USDC on Base mainnet or credit card. Supports certified/registered mail with proof of delivery and mail-merge templates.

Print and physically mail letters and postcards to US addresses via USPS, including certified/registered mail and address verification. Paid per call in USDC on Base via the x402 protocol, no signup.

PaymentOracle — ES256K-signed receipts for x402 payments on USDC+EURC (Base) and XRP+RLUSD (XRPL).