# coss.com vs Resend (https://coss.com/compare/resend)

> Resend and coss.com cover much of the same email ground. coss.com puts sub-accounts, sandbox environments and SMS on the same key.

Both are developer-first email APIs with SDKs, receiving and inboxes for agents. Resend has automations and a more collaborative inbox. coss.com is the choice when you send for your own customers, want a sandbox per environment, or need email next to SMS and one-time codes.

Facts about Resend checked on 2026-10-30 against the sources listed below.

## At a glance

| | coss.com | Resend |
| --- | --- | --- |
| Pricing model | Per recipient, with no volume tiers to pick: $0.40 per 1,000 recipients for the first 1,000,000; $0.30 per 1,000 recipients from 1,000,001 to 10,000,000; $0.22 per 1,000 recipients beyond 10,000,000. Paid plans start at $25/month, all of it spendable on usage | Monthly plans by email volume (Pro from $20/month for 50,000 emails, Scale from $90/month for 100,000); marketing priced by contacts (Pro marketing from $40/month for 5,000) |
| Free tier | Free plan: 3,000 email recipients a month, 3,000 received emails a month and 3 inboxes; 1 sending domain | 3,000 emails a month, at most 100 a day, 3 domains |
| Transactional email | REST API and an SMTP relay (smtp.coss.com), batch and scheduled sends, idempotency keys, templates with versions and locales | REST API and SMTP, templates with an editor |
| Marketing email | Contacts with custom properties, audiences, segments, topics with a hosted preference center and double opt-in, broadcasts on a separate marketing stream | Contacts, segments, topics, broadcasts and automations (10,000 automation runs a month included) |
| Receiving email | Every environment has its own address under coss.com's inbound domain, or receive at your own domain with one MX record; an email.received webhook, content and attachments through the API | Any address at a Resend-managed .resend.app subdomain, or your domain with an MX record; a webhook, then the content through its receiving API |
| Inboxes for agents | Inboxes give each agent its own address: mail kept as threads, replies from the same address; 3 inboxes included | Inboxes with threads, labels, drafts, folders, assignment and a configurable agent; 3 included, more at $1 per inbox a month |
| Multi-tenant sending | Sub-accounts on Scale and Enterprise: each with its own domains, SES tenant, reputation, quotas and suppression list (transactional email) | Its multi-tenant guide offers one account with domain-scoped API keys (one shared reputation) or a separate Resend account per tenant |
| Dedicated IPs | An add-on on Scale and Enterprise: Amazon SES managed dedicated IPs, warmed up automatically | $30/month add-on on Scale, for senders above 3,000 emails a day |
| Other channels | SMS, Verify (one-time codes), Hooks (webhooks as a service) and Risk on the same API key and SDK | Email |
| SDKs | TypeScript, plus generated SDKs for Python, Go, Ruby, PHP, Java and .NET; Laravel, Rails and Django mail drivers; a CLI and an MCP server | Node.js, PHP (and Laravel), Python, Ruby, Go, Java, Rust and .NET |
| Webhooks | Standard Webhooks signatures, automatic retries, test events and `coss listen` to forward events to localhost | Signed with Svix headers, with secret rotation through the API |
| Logs | Every API request, email event and webhook attempt of an environment, searchable and exportable; log drains on Scale and Enterprise | API logs in the dashboard and the API; 30 days of data retention on Free, Pro and Scale |

## When Resend is the better choice

- **You want automations.** Resend runs automation workflows on contacts. coss.com's marketing email is broadcasts you write and schedule, with segments and topics deciding who gets them.
- **Your team works in the inbox.** Resend's inboxes have labels, drafts, folders and assignment to teammates, and an agent you configure in the dashboard. coss.com's inboxes are threads an agent reads and replies to through the API.
- **You write Rust or Elixir.** Resend has an official Rust SDK and an Elixir quickstart. coss.com's SDKs cover TypeScript, Python, Go, Ruby, PHP, Java and .NET.

## When coss.com is the better choice

- **You send for your own customers.** A coss.com sub-account gives each of your users their own domains, SES tenant, reputation, quotas and suppressions, so one bad sender pauses only itself. Available on Scale and Enterprise; sandbox sub-accounts are free.
- **You want a real sandbox.** Every project has sandbox environments whose coss_test_ keys run the same API with nothing leaving coss.com, and a mailbox simulator for bounces and complaints.
- **Email is one channel of several.** SMS, one-time codes (Verify), Hooks and Risk use the same API key, SDK, webhooks and logs as email.
- **You debug from logs.** Each environment's log holds every API request, email event and webhook attempt, with lines about one email read as a single timeline.

## Moving from Resend

1. **Import your Resend account.** The dashboard's Import page reads your account with a full-access Resend key and brings over domains, templates, contacts with their properties, segments as audiences, topics, suppressions and webhook endpoints. Nothing changes at Resend. (/docs/migrate/resend)
2. **Verify your domains.** Add coss.com's DNS records next to Resend's. Both can sign your mail, so you keep sending through Resend until you switch. (/docs/email/domains)
3. **Switch your code and webhooks.** Replace the Resend client with coss.email.send(), which takes the same kind of fields (and React Email components), or point SMTP at smtp.coss.com. Imported webhook endpoints start disabled: update your handler to coss.com's events and signatures, then enable them. (/docs/webhooks)

## Frequently asked questions

### Can I move my Resend account to coss.com?

Yes. The dashboard's Import page copies domains, templates, contacts, segments, topics, suppressions and webhook endpoints from Resend with a full-access API key, and only reads your Resend account.

### Does coss.com work with React Email?

Yes. Pass a React Email component as react to coss.email.send() and the SDK renders it into HTML and plain text, with @react-email/render installed as an optional peer dependency.

### Does coss.com have inboxes for AI agents like Resend?

Yes. A coss.com inbox is an address for an agent: mail to it is kept as threads, an inbox.message.received webhook announces each message, and the agent replies from the same address through the API.

### Is coss.com cheaper than Resend?

It depends on your volume. coss.com charges per recipient with no volume tiers, and a paid plan's fee is credit spent on usage; Resend sells monthly plans by email volume and marketing plans by contacts. Compare both pricing pages with your own numbers.

### Do I have to change my webhook handler when I leave Resend?

Yes. coss.com has its own event names and signs requests with Standard Webhooks headers, so imported endpoints are created disabled with new secrets until your handler is updated.

## Sources

- [Resend pricing](https://resend.com/pricing)
- [Resend docs: receiving emails](https://resend.com/docs/dashboard/receiving/introduction)
- [Resend docs: Inboxes](https://resend.com/docs/dashboard/inboxes/introduction)
- [Resend docs: setting up Resend for multi-tenants](https://resend.com/docs/knowledge-base/setting-up-resend-for-multi-tenants)
- [Resend docs: SDKs](https://resend.com/docs/sdks)
- [Resend docs: verifying webhook requests](https://resend.com/docs/webhooks/verify-webhooks-requests)