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) |
|---|---|---|---|---|
| 25M–100M | 4th of 10 → | 3 | 8 |
| 10M–25M | 1st of 10 → | 9 | 9 |
From May 4th to August 2nd, Knock routed 25M–100M messages through Postmark and 10M–25M through Resend. Postmark reported 8 status page updates over the last 90 days, while Resend reported 9.
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 May 4th to August 2nd. The top-line number is an average of these daily values: Postmark averaged 5ms compared to 96ms for Resend. Postmark's highest daily p50 was 62ms; Resend's was 122ms. Postmark is 91ms 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 79ms compared to 168ms for Resend. The highest daily p90 was 222ms for Postmark and 221ms for Resend. Postmark handles these slower requests 89ms 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 305ms at p99 while Resend reached 496ms. The highest daily p99 was 1428ms for Postmark and 10906ms 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% | 0.08% | Jul 24 | 80 | 8 |
| 0.05% | 3.52% | Jul 29 | 83 | 5 |
Averaged across the date range, Postmark shows a 0.00% daily error rate compared to 0.05% for Resend. The highest single-day error rate was 0.08% for Postmark and 3.52% for Resend. Postmark demonstrates a lower error rate, indicating slightly more consistent availability during this period. 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 Jul 27, 2026 — Resolved Jul 28, 2026
The scheduled maintenance is now underway. We'll keep you updated on our progress.
Ongoing since Jul 20, 2026
We will be rescheduling the planned maintenance. Another status with the updated schedule will be posted.
Started Jul 6, 2026 — Resolved Jul 7, 2026
We've now resolved the incident. Thanks for your patience.
Started Jun 11, 2026 — Resolved Jun 12, 2026
All previously backlogged events have been processed. The issue occurred starting on June 11th at approximately 3:36am to June 12th 1:01pm CT (June 11th 08:36 – June 12th 18:01 UTC). Thank you for your patience. We will continue to improve our systems.
Started Jun 4, 2026 — Resolved Jun 5, 2026
The backlog of messages have been sent and system performance has returned to its expected state. Sending delays occurred between 4:50 – 6:35pm CT (21:50 – 23:35 UTC) for both transactional and broadcast mail. Engineering will continue to monitor.
Recent Resend incidents
Recent status page incidents for Resend
Started Jul 30, 2026 — Resolved Jul 30, 2026
Status: Resolved We have resolved the underlying issue, and service has resumed. Domain verification has been restored, and affected verifications were re-triggered. Affected components Dashboard (Operational) General API (Operational)
Started Jul 29, 2026 — Resolved Jul 29, 2026
Status: Resolved Between 20:15 and 20:16 UTC, a brief database disruption caused elevated error rates for approximately 45 seconds. During this window, requests to the Resend API, SMTP relay, and dashboard may have returned 5xx errors or timed out. The issue resolved automatically at 20:16 UTC and all services have been operating normally since. Any request that failed during this window can be safely retried. Emails that had already been accepted before the disruption were not lost. They were
Started Jul 29, 2026 — Resolved Jul 29, 2026
Status: Resolved We have resolved the underlying issue and service has been resumed. Affected components Single Email (Operational) Broadcast Emails (Operational) Batch Emails (Operational) General API (Operational)
Started Jul 22, 2026 — Resolved Jul 22, 2026
Status: Resolved We have resolved the underlying issue and service has been resumed. Affected components Dashboard (Operational) SMTP (Operational) Broadcast Emails (Operational) Batch Emails (Operational) General API (Operational) Webhooks (Operational) Website (Operational) Single Email (Operational) Email Events (Operational) Automations (Operational)
Started Jul 21, 2026 — Resolved Jul 21, 2026
Status: Resolved Delivery to Microsoft has returned to normal. Thank you for your patience as we worked with them regarding this.
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 5ms compared to 96ms for Resend.
Which is more reliable, Postmark or Resend?
From May 4th to August 2nd, Postmark showed an error rate of 0.00% while Resend showed 0.05%. 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 25M–100M messages from May 4th to August 2nd compared to 10M–25M for Resend. Postmark volume has remained stable, 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.