plainmailBest email for AI agents
Prices checked November 8, 2026
For an agent that runs mail on your own domains, and a mailbox you also read in Apple Mail, Plainmail fits best: $5 a month for 50 domains and 100 mailboxes, with the DNS written for you. If you're building a product that creates thousands of agent inboxes through an API, AgentMail is built for that. We make Plainmail, so weigh that, and the table shows where each one wins.
What to look for
- Your own domain. Mail from hello@yourproduct.com, signed with DKIM for that domain, lands in inboxes. Mail from a shared subdomain looks like a bot.
- MCP, not just an API. With an MCP server, Claude, Cursor and other clients can use the mailbox without you writing glue code.
- A human way in. Someone will need to read what the agent sent. IMAP lets you open the same mailbox in a normal mail app.
- Guardrails. Scoped permissions, sending limits, and email content treated as untrusted input, so a message can't steer the agent.
Side by side
| Plainmail | AgentMail | FranklyMail | Gmail / Workspace | |
|---|---|---|---|---|
| Price | $5 a month, flat | Free (3 inboxes); $20 a month (10 inboxes); $200 a month (150 inboxes) | About $9 a year, flat | $7 to $8.40 per user a month |
| Custom domains | Up to 50 | 1 free, 10 on Developer, 150 on Startup | Unlimited | One primary plus alias domains |
| Mailboxes | 100 | 3 / 10 / 150 by plan; $2 a month per extra | Unlimited | One per paid user |
| Sending | 200 per mailbox a day; no bulk mail | 100 a day free, 1,000 on Developer, 15,000 on Startup | Not listed | Gmail limits |
| MCP server | Yes, remote with OAuth; in the Claude directory | Yes, on every plan | Yes; every send needs your approval | Through third-party or Claude connectors |
| Writes your DNS | Yes on Cloudflare, Vercel, Porkbun | Not listed on its pricing page | No, you paste records | No |
| Mail apps (IMAP/SMTP) | Yes, plus a web inbox | Yes, IMAP and SMTP with an API key | Yes, IMAP and JMAP, plus webmail | Yes |
1. Plainmail: real mailboxes on your own domains
Best when you run several products or projects and want each to have hello@ and support@ that an agent can set up and answer. Claude can add the domain, write the DNS, create the mailbox and reply to mail, and you read the same mailbox in your own mail app. Not built for high-volume sending: 200 messages per mailbox a day, and no bulk or cold mail.
2. AgentMail: inboxes as an API
Best when your product creates inboxes for its users or agents on the fly. It has a free tier, an API built around inboxes, and send volume up to 15,000 a day on Startup. On a per-mailbox basis it costs more than flat-rate hosts once you pass the free tier: $20 a month covers 10 inboxes and 10 domains.
3. FranklyMail: cheapest flat rate, agent drafts only
Best when price matters most and you want the agent to read, sort and draft, but never send on its own. Every send through its MCP needs a human approval. You add DNS records by hand.
4. Gmail or Google Workspace: the inbox you already have
Best when the agent works in your own personal inbox. For project addresses it gets expensive: each separate inbox is a paid seat, and wiring the Gmail API means a Google Cloud project and OAuth app.
Pick by need
- Agent runs mail for your own domains, you read it too: Plainmail.
- Your app creates many inboxes by API, or sends thousands a day: AgentMail.
- Lowest price, human approves every send: FranklyMail.
- One personal inbox: Gmail with a connector.
Questions
Can Claude send email from my domain?
Yes, with an MCP mail server connected to a mailbox on your domain. With Plainmail you sign in once, choose what Claude may do (read, send, manage domains), and it sends from your address, signed with DKIM for your domain.
Is it safe to let an agent read email?
Email is untrusted input: a message can contain text that tries to give the agent instructions. Pick a server that marks email content as untrusted, lets you limit permissions, and caps daily sending. Plainmail does all three.
Do I need a separate domain for my agent?
No. You can give the agent its own address, like agent@yourdomain.com, on the domain you already use, or use a spare domain to keep its mail apart.
What's the difference between an email API and an email MCP server?
An API needs code you write and host. An MCP server plugs straight into Claude, Cursor and other MCP clients, so the agent can use mail with no glue code.
Get started$5 a month for up to 50 domains and 100 mailboxes