Sickle

Sickle's remote MCP server (https://mcp.sickle.app) connects every mailbox you own to Claude, Claude Code, Cursor, Codex or any MCP client: Gmail and Outlook over OAuth, plus iCloud, Fastmail, Yahoo and any IMAP server, all at once. Your agent can list, search, read, mark, move, trash, draft and send across all of those accounts, and work with attachments. Sign-in is OAuth with separate read, change and send scopes, and you can revoke each client on its own. It works from macOS, Windows or Linux, with nothing to install. Sickle is also a native macOS mail client for the same accounts: no cap on accounts, a colour per mailbox, an email cleaner for one-time codes and subscription junk, and keyboard/Vim navigation. £8.99/month or £30/year, with a 7-day free trial. One subscription covers the app and the MCP server.