Send & Retain vs Resend
Both are email APIs for developers, and both trigger emails from product events. Send & Retain is priced on sends and keeps every automation paused until you approve.
✓Free to start. Unlimited contacts on every tier.
One system, end to end
Product event accepted
Trigger
Paused automation inspected
Run
Delivery state retained
Report
[ 01 / 05 ]The short answer
What's the difference between Send & Retain and Resend?
Resend is a developer-first email API that also does broadcasts and automations. Send & Retain is an email API plus a remote MCP server, built so your AI agent runs your marketing automations and you approve what goes live.
- Both send transactional email from your code, and both use React Email templates.
- Both trigger automations from product events. Send & Retain creates every automation paused and has no broadcasts, by design.
- You don't have to pick one. Send & Retain can send through your own Resend key.
Receipt accepted
Details
deliveredDelivery events
- RequestIdempotency key verified
- SafetySuppression cleared
- ProviderDelivery accepted
- WebhookDelivered
[ 02 / 05 ]Side by side
How do Send & Retain and Resend compare?
Main job
Sending email from your code, plus broadcasts and automations
Transactional and marketing email in one system
Sending
Resend's own infrastructure
Our platform, or your own Resend or SendGrid key, with failover
Templates
React Email in code, or dashboard templates in a visual editor
React Email (TSX), versioned. Edits create drafts
Marketing email
Broadcasts to segments, and automations triggered by events
Automations triggered by what each user does. No broadcasts
Contacts
Contacts, segments, and topics
One record per person, with attributes, events, and history
Pricing
Plans by email volume, and by contacts for marketing
Priced on sends. Unlimited contacts on every tier
Agent access
Remote MCP server with browser sign-in, or an API key
Remote MCP server with browser sign-in. Automations stay paused until you approve
Safety checks
Bounce and complaint handling
Unsubscribes, suppressions, address checks, pause switch, and daily cap on every send
[ 03 / 05 ]Which to pick
Which should you choose?
Pick by the job you need done every week, not by the feature list.
- Choose Resend if you only send receipts and resets, or want to send newsletters to a segment.
- Choose Resend if you want broadcasts and automations from your sending provider, built in a visual editor.
- Choose Send & Retain if you want welcome, trial, and win-back emails triggered by product events.
- Choose Send & Retain if your AI agent should set up and run email, with every automation paused until you approve.
- Choose both if you like Resend's sending. Connect your Resend key and Send & Retain sends through it.
[ 04 / 05 ]For your app
What does sending look like in Send & Retain?
One call, idempotent by key. It returns an ID you can trace to the inbox.
Retry with the same key and it never sends twice.
const response = await fetch("https://sendandretain.com/api/v1/emails", {
method: "POST",
headers: { Authorization: `Bearer ${process.env.AEM_KEY}`,
"Content-Type": "application/json", "Idempotency-Key": `welcome-${user.id}` },
body: JSON.stringify({ to: user.email, template: "welcome" }),
});Accepted response
{ "id": "msg_7ca31", "status": "queued" }Questions people ask us
Try the automations. Keep your Resend key.
Connect your Resend key or use our sending, then build your first automation paused.