Pick Resend if your product already sends email and you want a few AI agents answering mail on the same domain and bill. It replaces a separate inbox vendor for small setups. Skip it for fleets of agent inboxes or long log retention: stored mail stays searchable for 30 days below Enterprise.
What changed
- · New feature Inboxes launched for every Resend user source
Resend is a developer email API, launched as a platform in 2023, that sends transactional and marketing email and, since 22 October 2026, hosts Inboxes: addresses on your own domain whose threads it stores for people and AI agents to read and answer through its API, CLI and an official MCP server.
About Resend
Resend began in 2022 as an open source project for building email templates that render properly in every mail client, then launched a full sending platform in 2023 and joined Y Combinator's winter batch that year. It is run by founders Zeno Rocha, Bu Kinoshita and Jonni Lundy with a fully remote team, and it announced an $18M Series A led by Andreessen Horowitz in December 2024.
What sets it apart in 2026 is that one account now covers three jobs that usually sit with different vendors: sending app email, receiving mail to your own webhook, and Inboxes, which Resend announced at its Resend Forward event on 21 October 2026 and opened to every user. An inbox is an address on one of your verified domains whose messages Resend stores and groups into threads, so a person and an AI agent can work the same conversation. Agents reach it through the REST API, the CLI or the official Resend MCP Server, which plugs into Cursor, Windsurf and other MCP clients.
The best fit is a product team that already sends receipts and password resets and wants a support or agent inbox without adding a second email vendor, or a builder giving an OpenClaw or Mastra agent its own address for tasks and approvals. Teams that need a fleet of agent inboxes are better served by AgentMail, which is built around that shape. For send-only alerts where logs must be kept for months, Postmark is the closer match, and Amazon SES wins on raw cost if you can build threading yourself.
The platform lists SOC 2 Type II and GDPR compliance on every plan, regular third-party penetration tests, signed webhook payloads and a configurable sending region. Inbound mail is not free capacity: Resend counts each received message against the same allowance as outgoing mail, which matters more for an agent inbox than for a notification sender. Our roundup of MCP servers covers how its MCP compares with other agent connectors.
Hokai files Resend in its email services directory, next to SendGrid and Cloudflare Email Service. Readers who want AI help inside their own Gmail or Outlook, not an API, should start with our AI email assistants roundup. Before an agent sends without a human check, our piece on approval gates for personal agents sets out where to put the stop.
Plans and pricing
Transactional plans as listed on 6 Nov 2026: Free $0 with 3,000 emails/month; Pro $20/mo (50,000) or $35/mo (100,000); Scale $90/mo (100,000), $160 (200,000), $350 (500,000), $650 (1M), $825 (1.5M) or $1,150 (2.5M); Enterprise custom. Overage per 1,000 runs from $0.90 on Pro to $0.46 on the largest Scale tier, and only applies once pay-as-you-go is switched on. Inbound mail and Inbox traffic draw on the transactional quota.
3 inboxes on every plan; more at $1 per inbox per month on paid plans only. Marketing plans are priced by contacts, from $40/mo for 5,000. Add-ons: 100 extra domains $20/mo, dedicated IP $30/mo on Scale, SSO $150/mo on Scale.
Monthly billing only; registered nonprofits can apply for 50% off.
Server plans
| Plan | Price |
|---|---|
| Free Cloud · 3,000 emails a month with a daily cap, 3 domains, 3 inboxes, 1 webhook endpoint · Multi-region | $0/mo |
| Pro 50k Cloud · 50,000 emails a month, no daily cap, 10 domains, 5 webhook endpoints · Multi-region | $20/mo |
| Pro 100k Cloud · 100,000 emails a month on the Pro feature set · Multi-region | $35/mo |
| Scale 100k Cloud · 1,000 domains, 10 webhook endpoints, Slack support, dedicated IP and SSO add-ons · Multi-region | $90/mo |
| Scale 2.5M Cloud · 2.5 million emails a month, the largest self-serve tier · Multi-region | $1,150/mo |
| Enterprise Cloud · Custom volume, uptime SLA, flexible retention, SSO included · Multi-region | — |
Key Features
- Inboxes for people and agents: Each inbox is an address on a verified domain with stored threads, labels, drafts and built-in inbox, sent, archive, trash and spam folders.
- Built-in inbox agent: A triage agent acts on each new message from written instructions, limited to the actions you enable, such as draft_reply or add_labels.
- Inbound webhooks: Receiving posts every message for a domain to your own endpoint with parsed content and attachments, separate from the stored Inboxes product.
- Hosted and local MCP server: mcp.resend.com takes an OAuth login or an API key, and the MIT-licensed resend-mcp package runs the same tools locally over stdio or HTTP.
- Batch sending: The Batch Email API sends a list of messages in one request, and the whole batch counts as a single call against the per-team rate limit.
- React Email templates: Templates can be written in React, TypeScript and Tailwind, the open source project the company started from.
Strengths
- App email and agent inboxes share one account, one dashboard and one bill, so a small team avoids running two email vendors.
- Stored, threaded inboxes remove the storage and threading code that a raw inbound webhook leaves you to write.
- Official SDKs cover Node, Python, PHP, Ruby, Go, Rust and Java, with matching examples in the Inboxes launch post.
Weaknesses
- The free plan caps sending at 100 a day and counts received mail against the same allowance, so a busy agent inbox can use it up on inbound alone.
- Stored mail and logs stay searchable for 30 days on Free, Pro and Scale; longer retention needs an Enterprise contract.
- Free allows a single webhook endpoint and cannot add a fourth inbox, and upgrading never raises the per-team API rate limit.
Frequently Asked Questions
How much do you pay for Resend?
Pro costs $20 a month for 50,000 emails or $35 for 100,000, and Scale runs from $90 for 100,000 up to $1,150 for 2.5 million, according to Resend's pricing page on 6 November 2026. Overage costs $0.90 per 1,000 on Pro and falls to $0.46 on the biggest Scale tier, but only if you switch pay-as-you-go on. Received mail and inbox traffic come out of the same allowance, and each inbox past the third adds $1 a month.
Is Resend free to use?
Yes, the Free plan does not expire and includes 3,000 emails a month, but it stops at 100 a day and counts each received message toward that allowance. It also gives you 3 domains, 3 inboxes with no option for a fourth, and one webhook endpoint. An agent inbox that receives a long thread can spend the day's allowance before it sends a single reply.
What should you use instead of Resend?
AgentMail is the better fit when you need dozens or hundreds of agent inboxes, with websockets and pods for keeping each customer's mail apart. Postmark suits send-only transactional mail where activity should be kept for months rather than weeks. Amazon SES is the cheapest per message if you are willing to store and thread inbound mail yourself.
Is Resend better than Postmark?
For an agent that has to read and answer mail, yes: Resend keeps inbound messages as threads in Inboxes, while Postmark parses them to JSON and posts them to your webhook, so storage is your job. Postmark is the stronger pick for send-only alerts and receipts, because its Pro and Platform plans let you keep activity for up to 365 days. Both providers count received mail toward billed volume.
How long does it take to get going with Resend?
Sign up with Google or GitHub, add the DNS records Resend generates to verify a domain, then create an API key and send through an SDK or SMTP. For an agent inbox, turn on receiving for that domain or set up forwarding, create the inbox, and connect your agent to the hosted MCP server, which opens a browser window for an OAuth login. DNS propagation is usually the slowest step.
Top Alternatives
- AgentMail: Pick Resend if you need a few agent inboxes next to app email; pick AgentMail for dozens of inboxes with websockets and pods.
- Postmark: Pick Resend if an agent must read and reply in stored threads; pick Postmark for send-only mail with activity kept up to a year.
- Amazon SES: Pick Resend for inboxes and a dashboard out of the box; pick Amazon SES when per-email cost matters more than build time.
- SendGrid: Pick Resend for a permanent free plan and agent inboxes; pick SendGrid if you already run Twilio and send millions a month.
Hokai guides that mention Resend
- Best Email APIs for AI Agents in 2026: Inbox or Webhook?: Six email APIs for AI agents compared: which give an agent a real inbox, what 10,000 emails each way cost, free-plan catches, retention and safety controls.