Yes. Anonymous inboxes and signed-in accounts are free, no card. We only charge for the paid plans — Pro and Team — which add more messages, longer retention, and custom domains soon. We'll never run ads, because third-party ad requests would break our no-outbound-network guarantee.

Anyone who knows the address can send to it, but reading requires the secret — held in an httpOnly cookie for anonymous inboxes, or your account for custom ones. Guessing an address grants send only, never read.

72 hours, then it’s purged automatically. It’s a test instrument, not a mailbox — don’t store anything you need to keep. Longer retention is a planned paid option.

Point your MCP client at https://mailmatter.dev/mcp with an API key — one line for Claude Code, a small JSON block for Cursor or VS Code. Your agent gets seven tools, including wait_for_email, which blocks until the message arrives. Not on MCP? Reading, waiting, and cleanup are available over plain REST too.

On the shared mailmatter.dev domain, yes — the name is part of the address, so it’s first-come. If you need a private namespace, a paid custom domain (coming soon) will give you one that’s entirely yours.

Not directly. Remote connectors there require OAuth with dynamic client registration; MailMatter authenticates with an org API key instead. Use the HTTP API, or bridge locally with mcp-remote. Claude Code, Cursor, and VS Code connect natively.