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 ↓ | 4 | 12 |
| 1M–10M | 1st of 10 → | 13 | 13 |
From July 4th to October 2nd, Knock routed 1M–10M messages through Postmark and 1M–10M through Resend. Postmark reported 12 status page updates over the last 90 days, while Resend reported 13.
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 July 4th to October 2nd. The top-line number is an average of these daily values: Postmark averaged 62ms compared to 87ms for Resend. Postmark's highest daily p50 was 209ms; Resend's was 96ms. Postmark is 25ms 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 209ms compared to 133ms for Resend. The highest daily p90 was 250ms for Postmark and 3594ms for Resend. Resend handles these slower requests 76ms 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 408ms at p99 while Resend reached 1157ms. The highest daily p99 was 1224ms for Postmark and 11263ms 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 | 89 | 0 |
| 0.00% | 0.09% | Oct 1 | 77 | 7 |
Averaged across the date range, Postmark shows a 0.00% daily error rate compared to 0.00% for Resend. The highest single-day error rate was 0.01% for Postmark and 0.09% 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 Sep 28, 2026 — Resolved Sep 28, 2026
This has been resolved. All inbound webhooks processing have been caught up. No messages have been lost.
Started Sep 28, 2026 — Resolved Sep 28, 2026
This incident has been resolved. The backlog of messages queued during the delay between 9:49 AM and 10:07 AM CT (10:49–11:07 AM ET) has been fully processed and delivered. New messages continue to be accepted and delivered normally. No messages were lost. If you have questions about a specific message, please reach out to us at [email protected].
Started Sep 22, 2026 — Resolved Sep 22, 2026
A subset of messages accepted between 2:15 pm and 2:35 pm EDT on September 22 (18:15 – 18:35 UTC) were held in queue due to a processing issue instead of being delivered immediately. Those messages were fully processed and delivered at 3:38 pm EDT on September 24 (19:38 UTC). No messages were lost. Messages accepted outside of this 20-minute window were not affected and were delivered normally. If you have questions about a specific message, please reach out to us at [email protected]
Started Sep 17, 2026 — Resolved Sep 17, 2026
Some users were experiencing problems with our service from 4:15 pm to 5:25 pm EDT, resulting in a page titled "Something went wrong". We have identified the root of the issue and have applied a remediating solution. If you are still encountering this page after clearing your site data, cache & cookies, please reach out to us at [email protected].
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.
Recent Resend incidents
Recent status page incidents for Resend
Started Oct 1, 2026 — Resolved Oct 1, 2026
Status: Resolved We have resolved the underlying issue and service has been resumed Affected components General API (Operational)
Ongoing since Oct 1, 2026
Status: Complete All systems are now fully operational Affected components Dashboard (Operational) Website (Operational)
Started Sep 26, 2026 — Resolved Sep 26, 2026
Status: Resolved We have resolved the underlying issue and service has been resumed. Affected components Webhooks (Operational)
Started Sep 24, 2026 — Resolved Sep 24, 2026
Status: Resolved We have resolved the underlying issue and service has been resumed. Affected components General API (Operational) Scheduled Emails (Operational) Single Email (Operational) Dashboard (Operational) Broadcast Emails (Operational) Batch Emails (Operational)
Started Sep 22, 2026 — Resolved Sep 22, 2026
Status: Resolved We have resolved the underlying issue and service has been resumed. Affected components Email Events (Operational) General API (Operational)
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 62ms compared to 87ms for Resend.
Which is more reliable, Postmark or Resend?
From July 4th to October 2nd, Postmark showed an error rate of 0.00% while Resend showed 0.00%. 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 July 4th to October 2nd 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.