The best thing about Mailbox MCP is what it leaves alone. We gave Claude and ChatGPT full control of our test mailbox for five business days to execute their operations. The system kept unread messages unhandled while it placed response messages into their correct discussion threads and maintained 1 copy of every sent message in the Sent folder. Small things, until an AI assistant gets them wrong in front of a customer.
Disclosure: Mailbox MCP gave KittyLaunch complimentary Pro access for this Mailbox MCP review. The company did not ask for a positive write-up and did not see this article before it was published.
What it is, in one paragraph
Mailbox MCP is a hosted remote MCP server run by BSolve IT Limited, a UK company registered in England and Wales.To get started, go to the dashboard. The dashboard enables you to link your existing mailbox while you need to paste one connector URL into Claude and ChatGPT and Cursor and other MCP clients. The assistant can read, search, reply, forward, draft and file mail in that inbox. You don't install anything, and your mail doesn't move anywhere. According to the vendor, no copy of your mail, calendar or contacts is kept. Each request is fetched from your provider, passed to the AI, and then dropped. Details are on the official Mailbox MCP website.
How Mailbox MCP works with any IMAP mailbox
Mailbox MCP has step-by-step guides for Microsoft 365, Outlook.com and Hotmail and Gmail and Google Workspace. It also works with any other provider that offers IMAP and SMTP. That is how we connected for this review, using a new Yandex Mail account.
Setting up IMAP is usually the annoying part. Many email MCP servers expect you to dig up server names and port numbers yourself. Mailbox MCP has a Find my settings button instead. You type in the email address, and it works out the provider and fills in the IMAP and SMTP details for you. Our Yandex account was connected within minutes.
Next, the control panel asks you to connect your AI. You don't have to write any MCP configuration. Mailbox MCP is already listed in ChatGPT's Plugins directory and in Claude's Connectors directory, so you search for it, click add, sign in and choose a permission level.
There are 3 levels. Read only gives the AI 16 of the 37 email tools. Draft and file gives it 30, but it cannot send or delete anything. Send and delete gives it all 37.
These permission levels turned out to be the most important setting in the product. With the connection set to Draft and file, we asked Claude to send a reply. The server refused, rather than the chat app just showing a warning. The security page says the level is checked on every call, and that is what we saw.
It is also easy to see what the AI has been doing. The control panel has an Activity page which shows all AI operations performed within the mailbox along with the complete history of MCP tool activations. Users who feel anxious about granting their inbox access to an assistant can verify every item the assistant accessed, created, drafted and sent.
5 working days with a test customer
Before we started, Mark McNeece from the Mailbox MCP team suggested we focus on the details that are easy to promise and hard to get right. So we built the test around a short support conversation with a test customer over several days. It included a question about an invoice, with the PDF attached, and an overnight follow-up that we left unanswered.
Every morning, we asked Claude to identify all new arrivals from the previous night and track which discussions still needed responses. The system located the follow-up from the previous night and identified 2 unresolved questions which remained in the report. The system provided us with the entire discussion history from that customer starting Monday instead of showing only their most recent message.
Replies kept their place in the conversation. Messages sent through the assistant appeared in the original thread, both in Yandex Mail and in the customer's inbox, with no stray new threads. Each sent message showed up exactly once in the Sent folder.
Drafts ended up being the feature we leaned on most. We kept the connection on Draft and file, so ChatGPT wrote its replies straight into the normal Drafts folder. From there, we opened them and finished them ourselves. When we asked for a second version, it replaced the old draft instead of leaving 2 copies.
Reading never changed anything. The unread count was the same before and after the assistant went through the conversation. Messages were only marked as read when we asked for that.
Attachments worked as promised. Claude opened the invoice PDF, read the seat count inside it and summarised it in the chat. We then asked it to forward that email to another address, and the PDF arrived identical to the original. A message with attachments adding up to more than 20 MB was refused, with a clear explanation.
Where it pushed back
We also asked Claude to follow up with the customer at 9am the next morning. Claude set this up as a scheduled task in its own app, not in Mailbox MCP. Its plan was to check at 9am whether the customer had replied, send a short response if she had, and let us know if she hadn't. The Mailbox MCP Activity page showed no scheduling tool at all, which matches the vendor's statement that its server never holds email to send later. Scheduling depends on your AI client, not on Mailbox MCP.
Bcc does not work, by design. When we asked Claude to Bcc a manager on a reply, it explained that Mailbox MCP does not support Bcc and did not send anything. It also paused the 9am follow-up, so that email would not go out without the manager, and offered to use Cc instead.
Mailbox MCP also says it cannot connect shared or delegated Exchange mailboxes. We did not test this.
The free plan is small. It allows 5 MCP calls per mailbox per day, and every tool the AI uses counts as one call. Finding a thread, reading it and sending a reply already uses 3. Those 5 calls are enough to try the product, but not to run a real mailbox day to day.
In Claude, a custom connector asks for your approval before every tool call. That is safe, but slow when you are working through a busy inbox. What worked for us was setting the read-only tools to always allow and keeping approval on everything that writes.
Why not just use the built-in Gmail or Outlook connector?
Mailbox MCP has published a comparison with the email connectors built into Claude and ChatGPT, quoting those vendors' own documentation. The differences are specific. Claude's Gmail connector can see that an email has an attachment but cannot read what is inside it. Claude's Microsoft 365 connector cannot send, forward or draft emails with attachments, and it does not work with personal Outlook.com or Hotmail accounts. Claude's Gmail connector also only reaches the one Google account you connected.
Mailbox MCP reads what is inside PDFs, sends and forwards attachments, saves drafts where any email app can open them, and works with any IMAP mailbox. Our Yandex account is a good example, because none of the built-in connectors can reach it at all.
Pricing
Pro costs £34.99 plus VAT a year per mailbox, which works out at £2.92 a month. It allows up to 1,000 calls per mailbox per day. If several people need their own access to the same account, Team Access adds 3 named users for £119.99 plus VAT a year, on top of Pro. The Mailbox MCP pricing page has the full details.
Prompt injection is the part we could not test
An AI that reads your email is also reading messages written by strangers, and some of those messages may try to give the AI orders. To test this, we sent the mailbox an email asking the assistant to forward recent invoices to an outside address. It never arrived. Yandex's spam filter rejected it before it reached the inbox, so we could not see how Mailbox MCP and Claude would deal with it.
Mailbox MCP's own security page is upfront about this risk. It describes its protection as "partially mitigated" and admits that it cannot block an email that simply asks the AI, in plain language, to do something. That is why we would start with Draft and file. The AI can prepare replies, but nothing is sent until a person presses send.
Who should pay for it
Mailbox MCP provides an ideal solution for individual users and groups who access their email through Outlook, Microsoft 365, Gmail or any IMAP mailbox but want Claude or ChatGPT to handle their email sorting and searching and drafting without altering their original data. The solution does not match well with users who depend on shared Exchange mailboxes or require Bcc functionality.
The product summary is on Mailbox MCP's KittyLaunch listing, and the maker is on the support2aaf maker profile on KittyLaunch.