Resend built its name on sending email: the password resets, receipts and alerts that developers send through its API. With Resend Inboxes, announced on 22 October 2026, it now covers receiving too, with one shared inbox where your team and your AI agents read, sort and draft replies on the same thread.
Key takeaways
- Each inbox is a real address on your own domain, such as support@example.com, with threads, folders, labels, search and drafts.
- A built-in agent can take 7 actions, and you pick which ones it may use. None of them is “send”.
- Outside agents such as Claude Code, Cursor and Codex connect through MCP or skills.
- You get 3 inboxes free. Each extra inbox costs $1 a month on a paid plan.
What is Resend Inboxes, exactly?
It is a shared inbox you control through an API. According to Resend’s launch post, each inbox sends and receives email at an address on your domain. Messages are grouped into threads that your app, your teammates and your agents can all reach.
You get the parts you would expect from a mail client: inbox, archive, spam, trash and sent folders, Gmail-style search, labels, drafts, forwarding, and reply-all with CC and BCC. Teammates can assign conversations to each other and leave notes.
Two features are clearly aimed at developers. Webhooks fire on events such as inbox.email.received and inbox.thread.assigned. Idempotency keys (a unique tag on a request, so a retry never sends the same reply twice) protect you when your code fails halfway through.
The launch builds on Resend Inbound, which arrived in November 2025. Inbound parsed each incoming email into JSON and posted it to your webhook. Think of Inbound as a mail slot. Inboxes adds the front desk: someone tracks every letter, who owns it and what happened next.
What can the Resend Inboxes agent actually do?
Every inbox has its own agent. You give it written instructions of up to 4,000 characters and pick one of four tones: concise or expanded, each in a professional or casual style. Then you choose which actions it may take. The API reference lists seven:
| Action | API name | What it does |
|---|---|---|
| Draft a reply | draft_reply | Writes a response for a human to review |
| Forward | forward_thread | Sends the thread on, such as invoices to finance |
| Label | add_labels | Tags threads for triage |
| Assign | assign_thread | Hands a thread to a teammate |
| Mark as spam | mark_as_spam | Moves junk out of the way |
| Archive | archive | Clears old or finished threads |
| Trash | move_to_trash | Deletes a thread |
Resend suggests you start with drafts and labels only. That is sensible advice. An agent that labels a thread wrong costs you a few seconds. An agent that trashes a customer’s refund request costs you the customer.
Notice what is missing from the list. The built-in agent has no “send” action, so its replies wait as drafts until a person approves them. Your own agents connected through the API are a different case. What they can do depends on the access you give them.
How do you connect Claude Code, Cursor or Codex?
Through MCP (Model Context Protocol, the common standard that lets AI assistants call outside tools) or through skills, which are packaged instructions an agent loads when it needs them. The product page names Claude Code, Cursor, Codex, Grok and Gemini as compatible.
Creating an inbox takes one call, resend.inboxes.create, with an email address, a name and a display name. From there your agent can search threads, read messages and post drafts. If you are building your own MCP server around a setup like this, our guide to scoring an MCP server with QAmcp is a useful check before you trust it with live mail.
Resend lists use cases such as support queues, recruiting pipelines, on-call alert inboxes, executive-assistant triage, and a dedicated address an agent uses for approvals and updates.
How much does it cost?
The free tier includes 3 inboxes and 3,000 emails sent or received, with no credit card. Free accounts cannot add more inboxes.
Each additional inbox costs $1 a month on pay-as-you-go, which you can only turn on with a paid plan. Resend’s pricing page lists Pro from $20 a month for 50,000 emails and Scale from $90 a month for 100,000 emails.
Here is the catch worth planning for: inbox email counts toward your transactional quota. In my view, a busy support inbox and your password-reset emails now draw on the same allowance, so size your plan for both.
How does it compare with AgentMail?
AgentMail, a startup that sells email built for AI agents, published a comparison on 30 April 2026. Treat it as a rival’s view, not a neutral review. Still, it makes the difference clear:
- Resend: shared team inboxes on your verified domain, with the built-in agent drafting while people stay in charge.
- AgentMail: the inbox belongs to the agent, can be created without DNS setup, and can reply on its own.
If you already send through Resend and want humans in the loop, Inboxes is the easy fit. If you want fully autonomous agents with their own addresses, the products are aimed at different jobs.
What happens next
Early Product Hunt commenters asked two questions without official answers on the page: whether Inboxes supports cold outbound email, and how it handles a person and an agent replying to the same thread at once. Watch for those answers, plus any new actions added to the list of seven.
The bigger trend is plain. Tools are being rebuilt so agents can use them directly, as with WebMCP across 100,000 online stores. Email was always going to be next.
FAQ
Can the Resend Inboxes agent send email by itself?
The built-in agent’s action list has no send action. It drafts replies, and a person sends them. Agents you connect through the API act within the permissions you give them.
Is Resend Inboxes free?
Yes, for up to 3 inboxes and 3,000 emails. Extra inboxes cost $1 each per month and need a paid Pro or Scale plan.
Do I need my own domain?
Yes. Inboxes are addresses on your own domain, such as support@example.com, so you verify the domain with Resend first.
Before you switch on more than drafts and labels, run your setup through our 7-point AI agent evaluation checklist.
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