Postmark vs Resend
Compare Postmark and Resend based on observed API performance, features, and pricing
Live performance comparison
Real-world performance data from messages sent through Knock
| Provider | Message volume | Growth | Status page updates (30d) | Status page updates (90d) |
|---|---|---|---|---|
| 1M–10M | 4th of 10 ↓ | 5 | 10 |
| 1M–10M | 1st of 10 → | 7 | 7 |
From June 3rd to September 1st, Knock routed 1M–10M messages through Postmark and 1M–10M through Resend. Postmark reported 10 status page updates over the last 90 days, while Resend reported 7.
Response time
Response time measures how long each provider takes to accept an API request from Knock, including connection overhead and any automatic retries. Lower values mean faster message hand-off.
The chart above shows each provider's daily median response time (p50) from June 3rd to September 1st. The top-line number is an average of these daily values: Postmark averaged 61ms compared to 90ms for Resend. Postmark's highest daily p50 was 209ms; Resend's was 106ms. Postmark is 29ms faster at the median, which can add up at high volumes.
The 90th percentile (p90) captures the slowest 10% of requests, revealing how each provider handles moderate stress. Averaged across all days, Postmark has a p90 of 212ms compared to 144ms for Resend. The highest daily p90 was 582ms for Postmark and 3588ms for Resend. Resend handles these slower requests 68ms faster, suggesting more consistent performance across the board.
The 99th percentile (p99) represents the long tail — the slowest 1% of requests. Averaged across all days, Postmark reached 558ms at p99 while Resend reached 1196ms. The highest daily p99 was 1224ms for Postmark and 19930ms for Resend, indicating the worst-case response time during spikes or provider-side congestion. Postmark shows a tighter tail, which may matter for time-sensitive notifications like one-time passwords or real-time alerts where even rare delays can impact user experience.
Error rate
Error rate tracks the ratio of 5xx responses and timeouts to total requests. Knock automatically retries failed requests, so transient provider errors rarely affect end-user delivery.
| Provider | Avg. daily error rate | Highest daily rate | Peak error date | Zero-error days | Days above 0.01% |
|---|---|---|---|---|---|
| 0.00% | 0.01% | Aug 30 | 90 | 0 |
| 0.02% | 1.28% | Jul 1 | 76 | 8 |
Averaged across the date range, Postmark shows a 0.00% daily error rate compared to 0.02% for Resend. The highest single-day error rate was 0.01% for Postmark and 1.28% for Resend. Both providers show similar reliability levels, with error rates well within acceptable thresholds. Knock automatically retries failed requests to both providers, minimizing the impact of transient errors on end-user delivery.
About these metrics: Data represents messages sent through Knock during the specified period. Response time measures time from Knock to provider acceptance. Error rate includes only provider 5xx responses and timeouts.
Recent Postmark incidents
Recent status page incidents for Postmark
Started Aug 24, 2026 — Resolved Aug 24, 2026
We've now resolved the incident. Stats data has caught up and is now displaying in real time. This issue occurred from approximately 13:45 EDT to 16:25 EDT on August 24, 2026. Thank you for your patience.
Started Aug 18, 2026 — Resolved Aug 19, 2026
The issue is now fully resolved. We are continuing to improve our systems, observability, and monitoring to prevent future occurrences. Thank you for your patience. Starting August 18th at ~9:34am CT (~14:34 UTC), Postmark experienced delays in delivering open webhook events. New open events resumed delivery on August 19th at ~8:47am CT (~13:47 UTC), and all backlogged events completed re-delivery at ~4:52pm CT (~21:52 UTC).
Started Aug 18, 2026 — Resolved Aug 18, 2026
The maintenance is now complete. Thanks for your patience.
Started Aug 14, 2026 — Resolved Aug 15, 2026
The issue has been resolved after additional monitoring into the early morning. Thank you for your patience.
Started Aug 7, 2026 — Resolved Aug 7, 2026
The maintenance is now complete. Thanks for your patience.
Recent Resend incidents
Recent status page incidents for Resend
Started Aug 20, 2026 — Resolved Aug 20, 2026
Status: Resolved We have resolved the underlying issue and service latency has been recovered. Affected components General API (Operational)
Started Aug 19, 2026 — Resolved Aug 19, 2026
Status: Resolved We have resolved the underlying issue and service has been resumed. Affected components Webhooks (Operational)
Started Aug 16, 2026 — Resolved Aug 16, 2026
Status: Resolved API became unstable from 12:54 to 12:57 UTC, returning 5xx for approximately 7% of the requests. We have resolved the underlying issue and service has been resumed.
Started Aug 13, 2026 — Resolved Aug 13, 2026
Status: Resolved Between approximately 17:30 and 17:43 UTC, requests to add a new domain failed in the dashboard and through the public API (POST /domains). Verification of domains added during this window was also affected. The issue was identified and fixed, and domain creation has returned to normal. No domains were partially created: affected requests failed immediately, so retrying the domain creation will succeed. Email sending for existing domains was not affected. Affected components
Started Aug 9, 2026 — Resolved Aug 9, 2026
Status: Resolved We have resolved the underlying issue and service has been resumed.
Pros and cons
Postmark
Resend
Pros
- Excellent deliverability with separate infrastructure for transactional and bulk messages
- Publishes time-to-inbox data across major email providers for transparency
- Great documentation with official and community-supported SDKs for all major languages
- 45-day message and log retention on all plans
Pros
- Beautiful documentation with attention to detail and great developer experience
- Created and maintain React Email, the go-to framework for building email templates in React
- Minimalist, developer-optimized platform that avoids bloat with a focused UI
- Transparent observability with real-time visibility into sends, failures, and engagement
Cons
- No visual drag-and-drop email editor
- Less suited for high-volume marketing email
- Smaller feature set compared to all-in-one platforms
Cons
- Newer and less battle-tested compared to incumbents like Mailgun or SendGrid
- Fewer enterprise features than established providers
- Limited marketing email capabilities
Frequently asked questions
What is the difference between Postmark and Resend?
Postmark is a transactional email service focused on fast, reliable delivery with transparent pricing. Resend is a modern email API built for developers, with React Email support and a focus on simplicity. Postmark is best suited for transactional email, while Resend is geared toward developer-first, react teams.
Which is cheaper, Postmark or Resend?
Free tier includes 100 emails per month. Paid plans start at $15/month for 10,000 emails with overages at $1.80/1K up to 125K, and $1.70/1K at 300K+. Free tier includes 3,000 emails per month and 100 emails per day. Paid plans start at $20/month for 50,000 emails with overages at $0.90/1K on Pro, scaling down to $0.46/1K on Scale 2.5M. The best value depends on your sending volume. Use the pricing calculator above to compare costs at your expected volume.
Which is faster, Postmark or Resend?
Based on real-world data from Knock, Postmark has a median API response time (p50) of 61ms compared to 90ms for Resend.
Which is more reliable, Postmark or Resend?
From June 3rd to September 1st, Postmark showed an error rate of 0.00% while Resend showed 0.02%. Both rates are within acceptable thresholds for production email delivery, and Knock automatically retries failed requests to minimize the impact of transient errors.
Which is more popular, Postmark or Resend?
On the Knock platform, Postmark handled 1M–10M messages from June 3rd to September 1st compared to 1M–10M for Resend. Postmark is currently seeing declining volume, while Resend volume has remained stable.
Can I use both Postmark and Resend together?
Yes. Knock enables you to integrate multiple email providers into a single notification workflow. You can use Postmark and Resend side by side, route traffic between them, or migrate from one to the other without changing your application code.
What are the main pros and cons of Postmark vs Resend?
Postmark strengths include excellent deliverability with separate infrastructure for transactional and bulk messages and publishes time-to-inbox data across major email providers for transparency. Resend strengths include beautiful documentation with attention to detail and great developer experience and created and maintain react email, the go-to framework for building email templates in react. On the other hand, Postmark drawbacks include no visual drag-and-drop email editor, while Resend drawbacks include newer and less battle-tested compared to incumbents like mailgun or sendgrid.
Use either provider with Knock
Knock enables you to integrate Postmark, Resend, or any combination of email providers into a single notification workflow. Manage templates, orchestrate cross-channel delivery, and switch providers without changing your code.