Your mailbox, in Claude, Cursor, or any MCP client.

Yes. Mailbox MCP is a remote MCP server that connects a mailbox you already own to Claude, so Claude can list, search and read messages, draft and send them, reply in thread, move mail between folders, archive it, report spam and flag it. Nothing in the server is specific to Claude, so the same mailbox works from Cursor or any other MCP client. It is your mailbox on your existing provider. Nothing is copied to a new address and there is nothing to migrate.

Yes, and this is the part most tools get wrong. Microsoft disabled Basic Authentication for IMAP on 1 October 2022, so a username and password cannot open a Microsoft 365 mailbox at all any more, no matter which client is asking. Mailbox MCP connects through Microsoft Graph with a single Microsoft sign-in instead. Sending goes through Graph too, which means you do not need Authenticated SMTP switched on and you do not need to involve your IT department to get it.

Because app passwords require 2-Step Verification backed by a phone or an authenticator app. Google documents the option as unavailable when 2-Step Verification is set up only for security keys, and a passkey behaves the same way: both replace the sign-in rather than adding a second step to it. Your account still reports 2-Step Verification as ON throughout, which is what makes this so hard to diagnose. That mismatch is what produces the message "The setting that you are looking for is not available for your account". Google now steers new accounts towards passkeys, so this is the default route into the dead end rather than an edge case. Add a phone number or an authenticator app to 2-Step Verification and the setting appears.

No, and you will not find the toggle if you go looking. Google removed it in January 2025 and IMAP is now always on for every Gmail account. Any guide still telling you to turn it on was written before that change and has not been revisited since.

Any AI client that supports remote MCP servers. Mailbox MCP is an ordinary MCP server reached over HTTPS with a bearer token, and nothing in it is specific to one assistant. It works in Claude on the web, the desktop app and Claude Code, and equally in Cursor, VS Code with agent mode, Zed, Cline, Goose, LibreChat, Microsoft Copilot Studio, or an agent you have written yourself against the MCP SDK. The one requirement is that your client can connect to a REMOTE MCP server rather than only a local one; clients limited to local servers can still reach it through a small proxy such as mcp-remote. Assistants with no MCP support at all cannot connect, and that list changes month to month, so check whether yours supports MCP connectors rather than trusting anyone's table of it.

No. Reading a message through Mailbox MCP leaves the unread flag exactly as it was, so your unread count is still yours and still means something. Marking a message read is a separate action that happens only when you ask for it.

They appear in Sent Items once, with the same Message-ID the recipient received, so your sent folder is a true record. Replies carry the In-Reply-To and References headers, which is what makes them land inside the existing conversation in Outlook or Gmail rather than starting a new one alongside it. Both behaviours were checked by comparing the folder before and after each send rather than assumed from the API response.

Yes, and this is where most email integrations fall down. A file can come from four places: one already in your mailbox, such as an invoice somebody sent you; one at a web address, like a SharePoint, Drive or Dropbox link; one from your own computer, through a one-off upload link that needs no sign-in; or one the assistant writes itself. The first three are streamed into the message when it is built and never pass through the assistant at all, so it does not have to encode the file, and a 6 MB PDF costs it no more than a sentence. That matters because the alternative is the assistant writing the whole file out as text, which is slow, expensive, and runs out of room long before the file does. Several files can go on one message, up to 10 MB in total. Only a file the assistant composes itself has to be written out, and only that one is limited to a few tens of kilobytes. A forward carries the original's own attachments and inline images as well.

Yes. A send, a reply, a forward or a draft can carry a read-receipt request, which is the same tick box Outlook offers, and a separate tool finds what came back afterwards. Be clear about what that can tell you, because the honest answer is less than people expect: a read receipt is a request to the recipient, not a measurement of them. Their mail program decides what to do with it, and most either ask them first or ignore it outright. Consumer Gmail never returns one, Google Workspace only if an administrator has enabled it, and Apple Mail only behind a setting that ships switched off. So a receipt that arrives means the message was opened and somebody agreed to say so, and a receipt that never arrives means nothing at all. The tool says exactly that in its own results rather than letting silence be read as being ignored. A delivery receipt is a different thing and is not offered: it needs an SMTP feature none of the mail providers this connects to support, so requesting one would appear to work and do nothing.

Every mailbox starts free with 5 MCP calls per day. Pro is £2.92 a month per mailbox, paid annually at £34.99 + VAT, renewing annually and paid by card through Stripe, and raises that ceiling to 1,000 calls per day. One account holds as many mailboxes as you like and Pro is bought per mailbox, so you can run one Pro mailbox alongside several free ones. You can stop the renewal on any mailbox at any time and Pro then runs to the end of the period you have paid for.

You can attach several files to a single message, but 10 MB is the total across all of them rather than a per-file allowance, so three 4 MB files are refused. That ceiling is ours rather than your provider's, and it applies whether the file is already in your mailbox, at a web address, or uploaded from your computer through a one-off link: none of those passes through the model. A file the assistant writes itself has to fit in its own output and is therefore far smaller, a few tens of kilobytes. It does not back up, export or migrate your mailbox, and nothing copies your mail anywhere; archiving a message files it in your own Archive folder rather than keeping a copy of it. It does not manage contacts or files. A calendar is reached only where one has been connected, which is its own step on top of connecting the mailbox, and there is a route for every mailbox: approving calendar access on a Microsoft 365 sign-in, signing in to Google for a Google calendar, or giving the address of a CalDAV server, which Fastmail, iCloud, Nextcloud and most hosts run. A mailbox with no calendar connected reads and writes mail and nothing beyond that, and is handed no calendar tools at all rather than tools that would refuse.