Mails.so MCP server
3 operations0 webhooks
Email address validation with Mails.so - check one address for deliverability, start a batch validation job for a list, and read the job back with its per-address results.
Try Mails.so with your agent
Connect Mails.so, then paste this into Claude, ChatGPT or Cursor. For ideas from other apps, see the use cases.
Using Corsair, show me what you can do in Mails.so on my account, then run one read-only example and show me the result.
Mails.so tools and triggers
Tools are what your agent can do in Mails.so through Corsair's MCP server. Triggers are the Mails.so events a routine can start from.
Validations
- BatchWrite
Start a batch validation job for at least 2 different email addresses; Mails.so documents it as paid-plan only, but a free account with credits ran batches in our test, and an account without access gets MailssoSubscriptionRequiredError. The job cannot be deleted through the API. It returns the job at once with no results: follow it with validations.getBatch until status is completed (it reads processing meanwhile).
validations.batch
- Get BatchRead-only
Read a batch validation job by id: status processing while it runs, and once completed the counts per result and the validation of every address
validations.getBatch
- SingleRead-only
Validate one email address: deliverability result and reason, a 0-100 score, and format, domain, MX, block-list, catch-all, generic, disposable and free-provider checks
validations.single
Connect Mails.so to Claude, ChatGPT or Cursor
- 1
Connect Mails.so in Corsair
Add your Mails.so API key once in Corsair. Corsair stores the credential encrypted and makes the Mails.so API calls for your agent, so it never goes into a prompt or a config file. Connect Mails.so
If your link lets the agent add apps, you can skip this: it gives you a sign-in link the first time it needs Mails.so. On a ChatGPT personal plan, connect Mails.so here first.
- 2
Add Corsair's MCP server to your agent
Every client uses the same address:
https://mcp.corsair.dev/mcpOpen Customize → Connectors → Add custom connector, paste the address, then select Connect.Add a custom MCP server with the address and choose OAuth. Personal plans get read tools only.Add to CursorOr add this to~/.cursor/mcp.json. Cursor opens Corsair to sign in the first time it connects.{ "mcpServers": { "corsair": { "url": "https://mcp.corsair.dev/mcp" } } }Run this, then run/mcpin Claude Code to sign in.claude mcp add --transport http corsair https://mcp.corsair.dev/mcpCodex, Gemini CLI, VS Code, Zed and other clients with OAuth sign-in work the same way. Clients without it, such as GitHub Copilot's coding agent, use a link's own address and an API key. Setup for every client
- 3
Sign in and choose what needs your approval
Your client opens Corsair to sign in. Pick a link: the apps your agent can use and a mode that decides what it may do without asking. None of Mails.so's operations are destructive, so in the default Cautious mode they all run right away. Strict mode asks before each of its 1 write, and Read mode allows reads only.
FAQ
Install corsair and @corsair-dev/mailsso, add the Mails.so plugin, and connect with an API key. Then call methods like corsair.mailsso.api.validations.batch() from your app. Corsair keeps each tenant isolated.
Yes. Mails.so requires an API key from your Mails.so account or developer dashboard. Create credentials with access that matches what you automate, then paste them into Corsair or connect through managed auth in Hub.
Yes. One Corsair client can hit Mails.so, GitHub, Notion, Stripe, and the rest. Trigger Mails.so from a webhook, push updates to Slack, or chain actions across plugins. Same tenant context across integrations, plain TypeScript.
Teams use Corsair for email address validation with Mails.so - check one address for deliverability, start a batch validation job for a list, and read the job back with its per-address results. Common builds include sync jobs, admin tooling, and agents that call Mails.so APIs from your backend.
The SDK is open source. Self-host and you pay Corsair nothing for the integration layer. Hub bills for hosted auth and execution, not per Mails.so API call. Hub has a generous free tier. For hobby projects you can probably run the whole thing on free. Paid plans start to matter with more tenants or heavier traffic.
We maintain @corsair-dev/mailsso in the open repo. When Mails.so ships API changes, upgrade the package. Your call sites stay typed. You should not need to rewrite the integration layer each time.
No. Corsair does not read your Mails.so data or hold individual access credentials. Credentials stay in your database. API calls run on your instance. We do not store Mails.so data on your behalf.
Yes. Add https://mcp.corsair.dev/mcp as a custom connector or MCP server in Claude, ChatGPT, Cursor, VS Code, Claude Code, Codex or any client that supports remote MCP servers with OAuth sign-in, then sign in to Corsair. On ChatGPT personal plans, custom servers currently get read tools only.
Yes. Put Mails.so on a link in Strict mode and every write waits for your approval, while destructive actions are refused. None of the Mails.so operations are destructive, so the default Cautious mode runs them all without asking. You can change a link's mode at hub.corsair.dev/me.