MCP — TempMail

Written for the AI assistant: what these disposable mailboxes are for, and how to drive them.

This page is written for the AI assistant on the other side of the connection: what this service is good for, when not to use it, and how to drive it. If you are a human setting things up, you only need this:

Endpoint (Streamable HTTP, JSON-RPC 2.0):  https://temp.cl4.ru/mcp

Claude Code:      claude mcp add --transport http tempmail https://temp.cl4.ru/mcp
Claude Desktop:   Settings → Connectors → Add custom connector → paste the URL
mcp.json:         { "mcpServers": { "tempmail": { "type": "http", "url": "https://temp.cl4.ru/mcp" } } }
stdio-only client: npx mcp-remote https://temp.cl4.ru/mcp

No install, no API key, no account. Everything below is addressed to the assistant.

What this service is

TempMail hands out disposable mailboxes on @cl4.ru that receive mail. You create one in a single call, get its address instantly, and read whatever arrives — including the confirmation code, which the server extracts for you into a code field so you never have to parse the body yourself. Nothing is registered, nothing is paid for, and the mailbox is yours until you delete it.

Use it for

Signing up somewhere	A site the user wants to try but not hand their real inbox to. Create a mailbox, use the address in the form, take the code or activation link out of the mail that follows.
One-time codes & magic links	Any flow that mails a code, an OTP, or a login link — `wait_for_message` hands you the code field directly.
Testing your own email	Send from the app you are building to the mailbox and read the delivered message back: subject, text, HTML, attachments. A real end-to-end check that mail actually leaves your system and renders.
QA of signup funnels	Run the same registration repeatedly with a fresh address each time, without polluting anyone's inbox.
Downloads behind an email wall	Trials, whitepapers, one-off confirmations you will never need again.

Do not use it for

Anything the user would mind losing. Messages are deleted automatically after about a week and idle mailboxes disappear, so this is the wrong place for a real account, for password-recovery mail, for banking, or for anything that must be readable next month. It cannot send mail — there is no such tool and no such feature. And do not use it to evade a ban, to mass-register accounts, or to sign someone else up for anything.

How to use it

The normal task — «register me somewhere and confirm the address» — is three calls:

1  create_mailbox()
       -> { address: "sunnyowl42@cl4.ru", token: "a1b2…", password: "…" }

2  … fill the signup form with that address, submit it …

3  wait_for_message({ token: "a1b2…" })
       -> { from, subject, body_text,
            code: "481920",
            activation_url: "https://site.example/activate?k=…" }

Then type the code into the form, or open activation_url — whichever the site asked for. If the mail has not arrived yet the call returns timed_out: true together with a since_id; call it again with that since_id and you will not re-read the mail you already saw.

Two variations worth knowing:

Reuse an earlier mailbox:  login_mailbox({address, password}) -> token
Only mail from one sender: wait_for_message({token, from_contains: "site.example"})
Browse what is there:      list_messages({token}) -> ids -> get_message({token, id})
Clean up when done:        wipe_mailbox({token, confirm: true})

Tools

`list_domains`	—	Domains currently accepting mail. Rarely needed: create_mailbox picks one for you.
`create_mailbox`	local_part?, domain_id?, password?	Creates a mailbox. Returns `address`, `token`, `password`. The token authorizes every other call — keep it for the whole task.
`login_mailbox`	address, password	Returns the token of a mailbox you already created earlier.
`list_messages`	token, limit?, unseen_only?	Newest first: id, from, subject, preview, is_seen, has_attachments. Does not mark anything read.
`get_message`	id, token, format?, max_chars?, peek?	Full message plus `code` (confirmation code the server already extracted) and `activation_url`.
`wait_for_message`	token, timeout_sec?, since_id?, from_contains?	Blocks up to 25 s and returns the first new message in full. The main tool — do not poll list_messages in a loop.
`get_attachment`	id, token	One attachment inline, base64, up to 2 MB.
`delete_message`	id, token	Deletes one message.
`wipe_mailbox`	confirm, token	Deletes the mailbox and everything in it.
`list_my_mailboxes`	—	Only with a Telegram account session token in the Authorization header: every mailbox of that account.

Pass token on every call, or send it once as Authorization: Bearer <token> and omit the argument. A Telegram account session token works in that header too; then address picks which mailbox of the account you mean.

Rules that will bite you

Wait, don't poll	`wait_for_message` already blocks for up to 25 s. Calling `list_messages` in a tight loop is slower and gets you rate-limited.
One mailbox per task	Creating mailboxes is limited to a handful per 15 minutes per IP. Reuse the address you already have instead of making a new one per attempt.
The token is a secret	It grants full access to the mailbox. Keep it in your own state; never type it into a web form or paste it into a page you are filling in.
Read the error text	Failures come back as tool results with `isError` and a sentence telling you what to do next (create a mailbox, pass a token, wait). Follow it rather than retrying the same call.
Mail can be slow	Some senders take a minute. Two or three `wait_for_message` calls in a row are normal; tell the user you are waiting rather than giving up after one.
Limits	80 MB per mailbox, ~7 days of retention, 20 MB per message, attachments over 2 MB must go through the REST API.

Also available

The same operations exist as a plain REST API — see API — and what the service stores is listed under Privacy. Humans can use the very same mailboxes in the browser at temp.cl4.ru with the address and password from create_mailbox.