Resend Review: Transactional and Marketing Email, Sender Isolation Done Right

We send our transactional and marketing email through Resend from two separate subdomains, on purpose — a marketing complaint should never be able to touch the deliverability of an OTP or password-reset email. That’s an architecture decision on our end, not a Resend feature, but it points at the real question anyone evaluating an email API should ask: how the provider handles domains, authentication, and the boring plumbing that determines whether your mail lands in an inbox or a spam folder.

TL;DR

Resend is a developer-first transactional and marketing email platform built around a REST API, an SMTP relay, and React Email for templating. The free tier gives you 3,000 emails a month (capped at 100 a day), and paid plans start at $20/month for 50,000 emails with no daily ceiling. It’s a strong fit if your team already writes React and wants email sending that feels like calling an API rather than configuring a legacy ESP. The biggest caveat: Resend is younger and narrower than incumbents like SendGrid — it doesn’t try to be a full marketing suite, and companies that need heavy segmentation, SMS, or a built-in CRM will outgrow it fast. We use it for both transactional and marketing/nurture email, kept on separate sending subdomains for reputation isolation, and initial domain verification (DKIM/SPF) worked on the first attempt.

Resend at a glance

What it is	Developer-focused email API: REST API + SMTP relay + React Email templating
Category	Transactional and marketing email infrastructure
Pricing model	Freemium, then tiered by monthly email volume with per-1,000 overage rates
Standout feature	Native React Email integration — templates written as React components
Free tier	3,000 emails/month, 100/day cap, 1 domain
Our usage	Transactional + marketing/nurture email, on separate sending subdomains

What Resend does

Resend is a San Francisco-based company founded in 2023 by Zeno Rocha and Bu Kinoshita, and went through Y Combinator’s Winter 2023 batch before raising a seed round backed by angels including Figma’s Dylan Field, Vercel’s Guillermo Rauch, and Supabase’s Paul Copplestone — a lineup that signals who Resend is building for: developer-tool founders who wanted an email API with the same design sensibility as the infrastructure tools they already used. The company later raised an $18M Series A on top of that seed.

Resend is marketed as the email API a developer would build: the goal is to make sending mail feel as simple as any other API call, instead of dropping the developer into a decades-old ESP dashboard. It covers both sides of the email problem: transactional sends (password resets, receipts, notifications) triggered from application code, and marketing/broadcast sends to contact lists, all from one account. The two flows share infrastructure but are billed and, on paid tiers, isolated separately.

Sending: API and SMTP

You can send through Resend’s REST API or through a standard SMTP relay, and both are available on every plan tier, including free. That matters for migration — teams running an existing SMTP-based mail setup (a WordPress site, an old cron job, a third-party tool that only speaks SMTP) can point it at Resend without rewriting anything, while newer code can call the API directly. Official SDKs cover Node.js, Python, Ruby, PHP, Go, Java, .NET, and Elixir.

React Email templating

Resend’s most distinctive feature is its tight integration with React Email, an open-source library (also maintained by the Resend team) for building email templates as React components instead of hand-coded HTML tables. Developers write a template using familiar JSX, preview it in a browser, and send it through Resend without touching a drag-and-drop editor. This is a meaningful differentiator versus legacy ESPs, whose templating tools are aimed at marketers, not engineers — but it’s also a reason non-technical marketing teams may find Resend less comfortable day-to-day than a visual builder.

Deliverability infrastructure and webhooks

Every tier, including free, gets DKIM/SPF/DMARC domain authentication, inbound email handling (receiving mail via webhook, added as a feature in 2025), open and click tracking, batch sending, and webhooks for delivery events — sent, delivered, bounced, complained, opened, clicked. Higher tiers add more verified domains, higher automation-run allowances, and (on Scale) the option of a dedicated sending IP, which larger senders use to control their own reputation rather than share a pool with other Resend customers.

Logs, analytics, and audit trail

Resend keeps a searchable log of every email sent through the account — status, timestamps, and the full event history for each message — which is useful when a customer says “I never got the email” and you need to check whether it was sent, bounced, or landed in spam. Retention windows vary by plan and by report, and are worth checking against your own compliance or debugging needs rather than assumed — a support ticket that lands three weeks after the fact is a bad time to discover your plan’s log window already expired.

Pricing

Plan	Price/mo	Transactional volume	Domains
Free	$0	3,000/mo (100/day cap)	1
Pro	$20–$35	50,000–100,000/mo	10
Scale	$90–$1,150	100,000–2.5M/mo	1,000
Enterprise	Custom	3M+/mo	Custom

Marketing (contact/broadcast) email is priced on a separate schedule based on contact count rather than send volume: a free tier for up to 1,000 contacts, then paid tiers from roughly $40/month for 5,000 contacts up to $650/month for 150,000 contacts, with custom Enterprise pricing above that. Overage on transactional plans runs from $0.90 per 1,000 emails on Pro down to $0.46 per 1,000 on the largest Scale tier — so heavy senders get a per-email discount as they grow, similar to most usage-based infrastructure pricing. What’s notably not gated behind a paywall: DKIM/SPF/DMARC authentication, webhooks, batch sending, and SOC 2 Type II compliance are included at every tier, including free — Resend doesn’t hold basic deliverability hygiene hostage to a plan upgrade the way some competitors do. What is gated is domain count (1 on Free, up to 1,000 on Scale), automation-run allowances, log retention, and support channel (ticket-only on Free and Pro, Slack access on Scale).

Pros

Deliverability essentials aren’t paywalled. DKIM, SPF, DMARC, webhooks, and SOC 2 Type II compliance ship on the free tier, not locked behind a $200/month plan the way some legacy ESPs structure things.

Both API and SMTP work on every tier. You’re not forced onto Resend’s API to get full functionality — an SMTP relay is a first-class option, useful for legacy systems or tools that only support SMTP.

React Email templating is a genuine differentiator. For teams already writing React, building transactional templates as components — with real preview, real diffs, real version control — beats maintaining hand-rolled HTML email markup.

Multi-domain support scales with plan tier rather than being an all-or-nothing feature, which works well for anyone running separate transactional and marketing subdomains, or multiple products under one account.

Inbound email and batch sending are included rather than sold as bolt-on add-ons, which keeps the pricing model relatively simple to reason about compared to providers with a longer menu of metered extras.

Cons

The free tier’s 100/day cap bites fast. 3,000 emails a month sounds generous until you realize you can’t send more than 100 in a single day even if you’re nowhere near the monthly limit — a real constraint if you’re testing multiple sending streams or doing a launch-day spike.

It’s not a marketing suite. There’s no built-in CRM, no SMS channel, no landing pages or popups — Resend does email and does it well, but teams that want one platform for every channel will need to bolt on separate tools.

Automations run on a separate meter from email volume. Free includes 10,000 automation runs a month; go over on a workload that leans heavily on automation and you’re billed per-run ($0.0015/run past the included amount) on top of your email plan, which is easy to lose track of.

Younger deliverability track record. Resend launched in 2023; providers like Postmark and SendGrid have a decade-plus of inbox-placement history and dedicated IP reputation management that a newer platform hasn’t had time to build to the same depth.

Marketing-contact pricing is a separate bill from transactional. Running both streams means tracking two different pricing schedules — one by email volume, one by contact count — instead of a single unified number.

How Resend compares

The most common comparison is Resend versus SendGrid versus Postmark, and each has a fairly clear lane. SendGrid, now part of Twilio, is the broadest and often cheapest at very high volume, and makes sense for teams already inside the Twilio ecosystem or that want marketing and transactional email from a single legacy-style vendor — but its API and dashboard show their age next to Resend’s, and SendGrid has historically mixed marketing and transactional traffic on shared infrastructure in ways that can hurt transactional deliverability if a marketing campaign gets flagged.

Postmark is the deliverability specialist: it separates transactional and marketing streams at the infrastructure level by design, and it’s frequently cited as having the best inbox placement of the three for pure transactional mail. Its pricing starts around $15/month for a production-viable tier (its free allotment is trial-only, not meant for real traffic), and it deliberately doesn’t try to be a marketing platform at all.

Resend sits between them: cleaner developer experience than SendGrid, a real (if newer) focus on deliverability, and — unlike Postmark — first-class support for marketing/broadcast sends alongside transactional, plus the React Email integration neither competitor offers natively. The tradeoff is maturity: Resend is the newest of the three, with less institutional deliverability history than either.

Who it’s for

Developer-led teams already using React. If your app is built in React or Next.js, React Email templates plug into your existing component workflow instead of forcing a separate email-building tool into the stack.

Startups that need both transactional and marketing email without two vendors. Resend covers both from one account and one API, which simplifies the stack versus running Postmark for transactional and a separate ESP for campaigns.

Teams migrating off legacy SMTP setups. Because Resend supports SMTP relay on every tier, you can swap in the new provider without rewriting the sending code first, then migrate to the API later if you want.

Not a fit for teams that need a full marketing platform. If you need SMS, a native CRM, landing pages, or deep behavioral segmentation in the same tool, Resend alone won’t cover it — you’ll be pairing it with something else.

Frequently asked questions

Is Resend free to use?

Yes — Resend’s free plan includes 3,000 emails per month, capped at 100 per day, one verified domain, and 30-day data retention. It’s usable for a small app or a low-traffic side project, but the daily cap makes it too restrictive for most production apps.

Does Resend support SMTP, or only its API?

Both. Resend offers a REST API and a standard SMTP relay on every plan, including free, so you can integrate however fits your existing code rather than being forced onto one method.

Can you send from multiple subdomains on one Resend account?

Yes — the number of verified domains scales by plan, from one on Free up to 1,000 on the Scale tier, which supports exactly the kind of subdomain isolation strategy (separating transactional from marketing sending identities) that deliverability best practice recommends.

What is React Email, and do you have to use React to use Resend?

React Email is an open-source templating library, also built by the Resend team, that lets you write email templates as React components. It’s the most convenient way to build templates for Resend but not mandatory — you can also send plain HTML or use one of Resend’s other SDKs without touching React.

How does Resend pricing compare to SendGrid at the same volume?

At the entry tier, they’re close: Resend’s Pro plan is $20/month for 50,000 emails, while SendGrid’s Essentials plan is roughly $19.95/month for the same volume. The gap widens at scale, where SendGrid’s broader feature set and longer-established infrastructure can work out cheaper per email for very high-volume senders.

Does Resend have its own dedicated IP option?

Yes, on the Scale plan. Dedicated IPs are optional there and let large senders manage their own sending reputation instead of sharing an IP pool, which matters once volume is high enough that a shared pool’s reputation could be affected by other Resend customers.

Is Resend good for marketing email, or just transactional?

Both are supported natively — Resend added contact/broadcast marketing email as a first-class feature, priced separately by contact count rather than send volume. It’s not as feature-rich for marketing as a dedicated ESP like Mailchimp or Klaviyo, but it works for straightforward newsletter and nurture sends.

What happens if you exceed your plan’s email limit?

You’re billed for overage rather than blocked outright, at rates that decrease as your plan tier increases — from $0.90 per 1,000 emails on Pro down to $0.46 per 1,000 on the top Scale tier.

Does Resend support inbound email (receiving, not just sending)?

Yes — Resend added inbound email handling in 2025, letting you receive email and route it to a webhook, which is useful for reply-tracking or parsing incoming support requests without standing up separate mail infrastructure.

Is Resend SOC 2 compliant?

Yes, Resend lists SOC 2 Type II compliance as a feature included across all plan tiers, not gated to Enterprise, which matters for teams that need to answer a vendor security questionnaire.

Who founded Resend, and how long has it been around?

Resend was founded in 2023 by Zeno Rocha and Bu Kinoshita, went through Y Combinator’s Winter 2023 batch, and has raised a seed round plus an $18M Series A. It’s a genuinely young company compared to SendGrid (founded 2009) or Postmark (2009), which is relevant if institutional deliverability track record matters to your evaluation.

Can Resend replace both your transactional and marketing email tools at once?

For straightforward use cases, yes — one account can send both transactional and contact-based marketing email. But it won’t replace a full marketing platform: there’s no built-in SMS, landing pages, or CRM, so teams with more complex marketing needs typically still pair Resend with a dedicated marketing tool for anything beyond email sending itself.

Verdict

Resend is a strong choice if your team is developer-led, already works in React, and wants email infrastructure that behaves like a modern API instead of a legacy ESP dashboard — and it’s genuinely competitive on price at low-to-mid volume, with deliverability fundamentals included instead of upsold. It’s a weaker fit if you need a full marketing platform (SMS, CRM, landing pages) in the same tool, or if your team specifically needs the decade-plus deliverability track record that Postmark or SendGrid can point to. For straightforward transactional plus marketing sending from one account, it’s worth trying the free tier before committing — just budget for the 100/day cap forcing an upgrade sooner than the 3,000/month number suggests.

See Resend’s full profile, pricing, and verified reviews on Spotsaas, listed under Email Testing Tools alongside its competitors.

Sources

• Resend — Pricing (checked July 2026)
• Resend — Documentation

Pricing verified July 2026 via Resend’s published pricing page and cross-checked against third-party comparison coverage. Features and prices change; this reflects the product as of July 2026. Written by the Spotsaas team, based partly on our own Resend setup.