Postmark vs Resend for low-volume transactional email (under 10,000/month)
This one splits cleanly on volume. Under ~3,000 emails a month, Resend wins and it isn't close: its free tier covers 3,000 emails/month (capped at 100/day, 1 domain) against Postmark's 100 emails/month — Postmark's free plan is a developer sandbox, not a production tier, and its first paid step is $15/month. Between ~3,000 and 10,000 a month the math flips to Postmark: Basic gives you 10,000 emails for $15/month while Resend's first paid plan is $20/month, and Postmark keeps 45 days of history on every plan against 30 days on Resend's free tier. Also mind Resend's caps: 100/day on free (a 300-signup launch day hits the wall) and a default API limit of 5 requests/second. We earn a commission on Postmark and nothing on Resend — the under-3,000 verdict goes to Resend anyway.
Side-by-side
| Postmark | Resend | |
|---|---|---|
| Free tier | 100 emails/month; “No overages allowed in this plan” | 3,000 emails/month, limited to 100 emails/day; 1 domain; 30-day data retention |
| First paid plan | Basic — $15.00/mo starting at 10,000 emails/month | Pro — $20/mo for 50,000 emails/month |
| Cost at 5,000 emails/mo | $15/mo (Basic; no tier exists between 100 free and 10,000) | $20/mo (Pro; free tier tops out at 3,000/mo) |
| Overage (first paid tier) | $1.80 per 1,000 (Basic) | $0.90 per 1,000 (Pro) |
| Data retention | 45 days on all plans (add-on to 365 days from $5/month) | 30 days on the free tier; paid-tier retention Not in the pricing data we captured — UNKNOWN |
| API rate limit | No published numeric limit — returns 429 when requests “exceed acceptable use”; exact threshold UNKNOWN | 5 requests per second per team (default) |
| Custom domains | 5 on Basic, 10 on Pro, unlimited on Platform | 1 on free, 10 on Pro |
| Batch sending | Batch API: max 500 messages per request; 10 MB per email, 50 MB per batch payload | Not in the pricing data we captured — UNKNOWN |
| Affiliate program | 20% of subscription for 12 months, no cap pays | None found as of 2026-07-12 no program |
- Resend's free tier is 3,000/month and 100/day — the daily cap is the one that bites bursty senders.
- Postmark has no plan between the 100-email free tier and 10,000 emails at $15 — there is no cheap middle step.
- Resend's default API limit is 5 requests/second per team; queue your sends if signups spike.
Where to sign up
Disclosure: we earn 20% of the first 12 months if you buy Postmark through the link above. Resend has no affiliate or referral program that we could find as of 2026-07-12, so recommending it earns us $0 — and we still recommend it below 3,000 emails/month.
FAQ
Is Resend really free for 3,000 emails a month?
Yes. Resend's pricing page (accessed 2026-07-12) lists a free tier of 3,000 transactional emails/month, limited to 100 emails per day, with 1 domain, 30-day data retention, and 1,000 marketing contacts.
Why is Postmark's free tier so small?
Postmark's free Developer plan is 100 emails/month with no overages allowed — it's for testing, not production. The first paid plan is Basic at $15.00/month, which starts at 10,000 emails/month.
Which is cheaper at 5,000 emails per month?
Postmark: $15/month (Basic) versus Resend's $20/month (Pro), because Resend's free tier tops out at 3,000/month and its next step is Pro. Below 3,000/month, Resend is free and Postmark costs $15.
What API rate limits should I plan for?
Resend's default is 5 requests per second per team (per its API docs, accessed 2026-07-12). Postmark publishes no numeric limit — its API returns a 429 when requests exceed acceptable use, and the exact threshold is unknown.
Sources
- https://postmarkapp.com/pricing (accessed 2026-07-12)
- https://postmarkapp.com/developer/api/overview (accessed 2026-07-12)
- https://postmarkapp.com/lp/referral-partner-program (accessed 2026-07-12)
- https://resend.com/pricing (accessed 2026-07-12)
- https://resend.com/docs/api-reference/introduction (accessed 2026-07-12)