Plug in. Done.
One-snippet setup for the runtime your agent already runs in. MCP-native for the agent IDEs, native SDKs for everything else.
Chat and coding agents
Claude
Add mails as a custom connector on claude.ai or Claude Desktop, then use it in any chat.
Claude Code
Add the hosted server with one command and sign in from /mcp in any session.
Codex
Add the server with codex mcp add; the CLI, IDE extension and app share it.
Cursor
Add the server to mcp.json and Cursor’s Agent can send, reply and read threads.
GitHub Copilot
Add mails in VS Code with MCP: Add Server, or give the cloud agent an API key.
Gemini
Add it with gemini mcp add and sign in with /mcp auth; Code Assist reads it too.
Windsurf
Add the server to mcp_config.json in Windsurf, now Devin Desktop, for Cascade.
Cline
Add the server in the MCP Servers panel; with auto-approve off, Cline asks first.
Continue
Add the server to config.yaml and use it in Agent mode in VS Code or JetBrains.
Apps built from a prompt
Lovable
Connect mails as an MCP server while you build; your app keeps its key in secrets.
Replit
Add the server once under Integrations and Replit Agent uses it in every project.
v0
Pick MCPs in v0’s + menu to use mails while it builds; your app reads its key from env.
Bolt
Add a custom connector, turn it on per project, and keep the API key in secrets.
Agent frameworks
OpenAI Agents SDK
Attach the MCP server to an agent, or wrap the SDK in function tools you control.
Anthropic SDK
Let Claude’s API call the hosted server through the MCP connector, or use the SDK.
Vercel AI SDK
Load the server’s tools with createMCPClient, or wrap the SDK in tool() calls.
LangGraph
Wrap the Python SDK as tools and bind them to any node in a StateGraph.
Pydantic AI
Give a typed Python agent tools to send and read mail, or load the MCP server.
One command
Add the server from your terminal
The CLI connects Claude, Claude Code, Cursor, Codex or VS Code to the hosted MCP server, and you sign in through your browser. Any file it changes is copied to a backup first.
npx @mailsai/cli mcp install --client claude-codeHow guides connect
Three ways to connect
Every guide uses one of three: the hosted MCP server, an SDK, or the REST API with a key.
Hosted MCP
Chat and coding agents add https://api.mails.ai/mcp and sign in. Nothing runs on your machine.
SDKs
Agent frameworks call the TypeScript or Python SDK from tools you define, with an API key.
REST API
Apps built from a prompt call the API themselves, with a key kept in the builder’s secrets.
Frequently asked questions
Which tools have a setup guide?
My tool is not listed. Can I still connect it?
Do I need an API key?
What is the difference between the MCP server and the SDKs?
Can I add the MCP server from my terminal?
Can apps I build in Lovable, Replit, v0 or Bolt send email?
Can my agent read the replies it gets?
What can’t an app connected over MCP do?
Is mails.ai free to try?
“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.”
“The 422 on cold outreach is the feature I didn’t know I wanted. An agent can’t talk itself into emailing strangers.”
“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