If you're a solo dev who just needs password resets, receipts, and notifications to actually land in the inbox, this guide is for you. I've shipped on all three of these, and the honest bottom line is short: Resend is the best starting point for a new project because the developer experience is genuinely better than everything else, but it's not automatically the right call if deliverability is your single biggest risk or you're sending at real volume.
Quick comparison#
| Resend | Postmark | Mailgun | |
|---|---|---|---|
| Free tier | 3,000/mo (100/day) | 100/mo (test only) | ~3,000/mo (100/day) |
| Paid entry (June 2026) | Pro $20/mo, 50k | Basic $15/mo, 10k | Basic $15/mo, 10k |
| Best at | Developer experience | Transactional deliverability | Volume + flexibility |
| Standout feature | React Email + modern SDKs | Message Streams | EU data residency |
| Developer experience | Excellent | Good, solid docs | Capable, more enterprise |
| EU data residency | No (sending region only) | No | Yes (US or EU) |
| Best for | New SaaS, best DX | Mission-critical transactional | High volume / bulk / EU |
All pricing below is dated June 2026. Plans change often — confirm current numbers on each provider's own pricing page before you commit.
How we picked#
For transactional email, the priorities aren't the same as for marketing. I weighted, in order: deliverability (does the email actually reach the inbox, and can you keep critical mail isolated from risky mail), developer experience (how fast you go from zero to a sent email, SDK quality, templating, logs), pricing at solo-dev volume (the free tier and the first paid tier matter far more than the enterprise rate), and domain auth and observability (SPF/DKIM/DMARC setup, plus logs you can actually debug with). EU data residency is a tiebreaker that becomes a hard requirement for some teams. I ignored marketing-automation depth except to note who does bulk well.
Resend#
Resend is the newest of the three and the one built for how people write code in 2026. The API is clean, the official SDKs (Node, Python, Go, Ruby, PHP, and more) are well-made, and the headline feature is React Email — a first-party library for building email templates as React components instead of hand-writing table-soup HTML. If your stack is already React/Next.js, this removes a whole category of pain.
The dashboard is the nicest of the three, domain verification is the most streamlined, and logs are clear. It's the fastest "install to first email" of the bunch.
Pricing (June 2026): Free tier is 3,000 emails/month, capped at 100/day, on one domain. Pro is $20/mo for 50,000 emails or $35/mo for 100,000, with overages at $0.90 per 1,000. Scale runs $90/mo (100k) up to $1,150/mo (2.5M) with overage dropping toward $0.46 per 1,000 at the top, and dedicated IPs are a $30/mo add-on on Scale, available once you exceed 3,000 daily sends. Marketing email is a separate product billed per contact — if you do both transactional and marketing, you pay two subscriptions.
Pros
- Best-in-class DX: clean API, strong SDKs, first-party React Email for templating
- Most usable free tier for shipping (3,000/mo) with the smoothest domain-auth flow
- Modern dashboard and clear, readable logs
Cons
- Youngest player — the shared-IP deliverability track record is shorter than Postmark's, and it doesn't enforce transactional/broadcast separation
- No true EU data residency: you can send from an EU region (Ireland), but account data, logs, and analytics still live in the US
- The 100/day free cap bites before the monthly total during spikes; marketing is a second paid subscription
Who should skip it: Teams with a hard EU-data-residency requirement, and anyone whose single biggest risk is deliverability at scale — Resend's track record is real but shorter, and it won't isolate a bad bulk send from your critical mail the way Postmark does.
Best for: A solo dev or small team shipping a new SaaS who wants the least-friction, most modern setup.
Start free on Resend →Affiliate link · how this worksPostmark#
Postmark is the long-standing gold standard for transactional deliverability and speed. It's been doing one thing well for over a decade: getting transactional mail into the inbox, fast, and giving you the logs to prove it. If a password reset that doesn't arrive turns into a support ticket and a churned user, this is the product that's obsessed with that exact problem.
The defining feature is Message Streams: transactional mail and broadcast/bulk mail run on separate infrastructure with separate reputation, so a bad marketing send can't poison the deliverability of your critical transactional email. Resend doesn't enforce that separation; Mailgun does it through separate domains and IP pools rather than a built-in concept. Postmark's send speed and reputation are consistently excellent, and its 45-day message history is searchable and useful for debugging.
Pricing (June 2026): The free tier is only 100 emails/month with no overages — it's a test allowance, not a launch tier. Paid plans all start at 10,000 emails: Basic $15/mo (overage $1.80 per 1,000), Pro $16.50/mo (overage $1.30, adds inbound and more streams), and Platform $18/mo (overage $1.20, unlimited streams and domains). Data history is 45 days by default; extending it up to 365 days is a paid add-on (from $5/mo) on Pro and Platform.
Pros
- Excellent, well-earned transactional deliverability and fast send speeds
- Message Streams cleanly isolate transactional from broadcast reputation
- Solid SDKs, clear docs, genuinely useful 45-day searchable logs
Cons
- Free tier is effectively useless for launch (100/mo) — you're paying from day one in production
- Stricter approval/anti-spam posture; they police what you send (good for reputation, occasionally annoying)
- No EU data residency, and not a full marketing platform if you need heavy campaign automation
Who should skip it: Anyone who wants to ship on a free tier, anyone who needs EU data residency, and teams whose primary need is heavy marketing automation rather than transactional reliability.
Best for: Any product where transactional deliverability is mission-critical and a missed email is a real problem.
Try Postmark →Affiliate link · how this worksMailgun#
Mailgun is the veteran — flexible, programmable, and built for scale and mixed workloads. It's been around far longer than Resend and leans more bulk/enterprise than the other two. If you're sending serious volume, doing both transactional and bulk, or you have a hard EU compliance requirement, Mailgun is the one that bends to fit.
It's the only one of the three with real EU data residency — you can send from and store data in the US or the EU from a single account, which matters for GDPR-strict teams (set the region at account setup; migrating later is disruptive). Mailgun also has deep features around routing, inbound email, validation, and analytics. The trade-off is that the developer experience feels more enterprise and less polished than Resend; there's more surface area to configure, and the dashboard shows its age in places.
Pricing (June 2026): Free tier is 100 emails/day (~3,000/mo) with 1-day log retention, one domain, and ticket-only support. Basic starts at $15/mo for 10,000 emails (overage $1.80 per 1,000, 1-day logs), Foundation is $35/mo for 50,000 (1,000 domains, 5-day logs, overage $1.30), and Scale is $90/mo for 100,000 with a dedicated IP included and 30-day logs (overage $1.10). So overages run roughly $1.10–$1.80 per 1,000 depending on plan.
Pros
- Built for volume and flexibility; handles transactional and bulk natively
- Only option here with true EU data residency (US or EU from one account)
- Deep routing, inbound, validation, and analytics tooling
Cons
- DX is more enterprise and clunkier than Resend; steeper setup for simple use cases
- Free and low tiers have stingy log retention (1 day on Free and Basic) — painful for debugging
- Deliverability reputation has historically been more variable than Postmark's; needs more hand-holding on warmup at volume
Who should skip it: Solo devs who just want the fastest, cleanest path to a sent email — Resend is less friction for that. Skip it too if short log retention on the cheap tiers would slow your debugging.
Best for: High-volume senders, mixed transactional + bulk needs, or anyone with an EU data-residency requirement.
See Mailgun plans →Affiliate link · how this worksWhich should you choose?#
- You're shipping a new SaaS and want the least friction: Resend. The React Email integration and clean SDKs save real time, and 3,000 free emails/month gets you to launch.
- A missed password reset is a fire drill: Postmark. Message Streams plus a decade-long deliverability track record is what you're paying for, and you should expect to pay from day one.
- You're sending high volume, doing bulk, or need EU residency: Mailgun. It's the flexible veteran and the only one here that keeps your data in the EU.
- You do both transactional and marketing: Decide where your risk is. Resend splits these into two products (two subscriptions); Mailgun handles both natively; Postmark stays transactional-first and routes broadcast through a separate stream.
- You're on a tight budget and just need a few thousand emails: Resend or Mailgun (both ~3,000/mo free). Postmark's 100/mo free won't cut it.
p=none to monitor, then tighten). With Gmail and Yahoo's bulk-sender rules now in force, skipping DMARC is the fastest way to land in spam regardless of which service you chose.One more money note: watch the overage rates, not just the base price. At a steady 10k–50k emails/month the entry plans are close, but if your volume is spiky, the per-1,000 overage (and on Mailgun, the short log retention on cheap tiers) is where the real cost and pain show up. Re-confirm all of these numbers on each provider's own pricing page before you commit — they change them more often than you'd think.