MCP server.
Install
One JSON block. That’s it.
Add one JSON block and your agent gets mails_* email tools in Claude Code, Cursor and most other MCP-capable runtimes. The npm package runs on your machine, with no server to host, and your API key stays there. Or point your client at the hosted server and sign in.
{
"mcpServers": {
"mails": {
"command": "npx",
"args": [
"-y",
"@mailsai/mcp-server"
],
"env": {
"MAILS_API_KEY":
"mk_live_..."
}
}
}
}Ask
Try asking your agent
Once the server is connected, ask in plain words. Copy any of these into your client.
“Send a test from the hello agent to reply@test.mails.ai”
“Thank the sender of the newest message in the hello inbox”
“List the threads that are still open for the hello agent”
“Draft a follow-up to dana@example.com for me to review before it sends”
“Is ops@example.com on our suppression list?”
“On Pro (5 agents), create an agent called invoices for sending receipts”
“Show me the replies the hello agent got since yesterday”
“How healthy is the hello agent’s sending reputation?”
“How much of this month’s allowance have we used?”
Tools exposed
A tool for every operation
your agent needs
Hand-named tools for everyday jobs, and a generated one for every other operation a key can call but the live event stream and the billing link. Nine of them:
Sending
mails_sendsends from any agent address and returns the message id and its status.Replying
mails_replyanswers in the same thread, with In-Reply-To and the Re: subject set.Inbound
mails_list_receivedpages through inbound mail with its attachments and SPF and DKIM results.Threads
mails_list_threadspages through conversations, grouped by In-Reply-To; open one for its history.Replies
mails_list_replieslists the replies an agent received, with a since filter for polling.Reputation
mails_get_reputationreturns an agent’s reputation score (0–1), built from real engagement.Suppression
mails_check_suppressionsays whether an address is suppressed before you send to it.Agents
mails_create_agentprovisions a per-agent identity bound to your sending domain.Drafts
mails_create_draftstages an email for a person to review before it is sent.
We added the hosted server in Claude, signed in once in the browser, and no API key ever sat in a config file.
In action
See the server in action
Watch Claude Code add the server, send a hello and read the reply. The same tools work in Cursor, Cline, Continue, Windsurf, the OpenAI Agents SDK and the Anthropic SDK.
“Replies come back as events with an injection score already on them. We deleted a whole layer of parsing code the week we switched, and we gate on the quarantine flag, so our agent never sees the ones that look like attacks.”
“Moving our agent onto our own domain was a few DNS records at the registrar. No nameserver move, and our existing mail kept working. Replies to the agent still come back to its inbox, threaded with the message they answer.”
“Our agent writes every reply as a draft, with a key that can’t send. Someone on the team reads it and hits Send now in the dashboard.”
“Our tests send to the test address and wait for the real reply, so the whole loop is covered before a customer ever writes in. It answers in about a second, which keeps the suite fast.”
“Adding the MCP server was one JSON block. Claude Code could send and read its own inbox a minute later.”
“A reputation score per agent tells us exactly which one needs attention, instead of one number for the whole account. It comes from each agent’s own replies, bounces and complaints, and we read it from the API.”
“Sends and replies have separate allowances, so a busy inbox never eats our sending quota. Pricing was the easy part.”
“Half our agents are LangGraph in Python and half are Node. Both SDKs make the same calls, so the team doesn’t have to think about it.”
“Signed webhooks, retries with backoff and an event id to dedupe on. The boring plumbing, done properly.”
“We signed up, made a key and sent our first message without talking to anyone, and the free tier never asked for a card. That’s how infrastructure should feel.”
Give your first agent an inbox
Free covers 3,000 emails and 3,000 inbound replies a month, with no card. Upgrade when your agents get busy.
Get your API key