Mailtrap vs Postmark
Compare Mailtrap and Postmark 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 | 7th of 10 → | 1 | 1 |
| 25M–100M | 4th of 10 → | 6 | 13 |
From January 22nd to April 22nd, Knock routed <1M messages through Mailtrap and 25M–100M through Postmark. Mailtrap reported 1 status page update over the last 90 days, while Postmark 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 January 22nd to April 22nd. The top-line number is an average of these daily values: Mailtrap averaged 93ms compared to 27ms for Postmark. Mailtrap's highest daily p50 was 197ms; Postmark's was 57ms. Postmark is 66ms 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, Mailtrap has a p90 of 219ms compared to 90ms for Postmark. The highest daily p90 was 926ms for Mailtrap and 143ms for Postmark. Postmark handles these slower requests 129ms 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, Mailtrap reached 994ms at p99 while Postmark reached 237ms. The highest daily p99 was 1651ms for Mailtrap and 38235ms for Postmark, 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% | 0.00% | Jan 22 | 91 | 0 |
| 0.03% | 2.37% | Mar 27 | 84 | 4 |
Averaged across the date range, Mailtrap shows a 0.00% daily error rate compared to 0.03% for Postmark. The highest single-day error rate was 0.00% for Mailtrap and 2.37% for Postmark. 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 Mailtrap incidents
Recent status page incidents for Mailtrap
Recent Postmark incidents
Recent status page incidents for Postmark
Started Apr 21, 2026 — Resolved Apr 21, 2026
Good news - this issue has been resolved and everything should be working normally now. We're continuing to monitor closely to make sure everything stays stable. Thank you so much for your patience while we worked through this.
Started Apr 8, 2026 — Resolved Apr 9, 2026
**[UPDATE]** We determined that yesterday's network instability was caused by a widespread Google (Gmail) outage. You can find more information on Google’s Status Dashboard here: https://www.google.com/appsstatus/dashboard/incidents/224ozRqzW4sFBDK8hLnT We will share an additional update regarding our internal action items later today.
Started Apr 2, 2026 — Resolved Apr 3, 2026
**[UPDATE]** On **April 2nd** starting at **~07:00pm UTC**, Postmark experienced an incident that resulted in delayed message delivery and webhook notifications for some customers. The issue was caused by an infrastructure configuration change that disrupted internal mail routing. While messages were safely queued in a "Processing" state, they were not delivered until the routing configuration was restored. Service was restored on **April 3rd at ~4:20am UTC** and the backlog of queued message
Started Mar 27, 2026 — Resolved Mar 28, 2026
We've resolved the incident. Thanks for your patience.
Started Mar 26, 2026 — Resolved Mar 26, 2026
The issue has been resolved.
Pros and cons
Mailtrap
Postmark
Pros
- Strong deliverability with dedicated IPs, auto warmup, and automatic authentication
- Great developer experience with comprehensive docs and MCP support for IDEs
- Combined testing sandbox and production sending in one platform
- Trusted by PayPal, Atlassian, Adobe, and Yelp
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
Cons
- Native integration ecosystem is smaller than established competitors
- Lower sending limits on free tier compared to some providers
- No rate limits by default, which may require custom throttling configuration
Cons
- No visual drag-and-drop email editor
- Less suited for high-volume marketing email
- Smaller feature set compared to all-in-one platforms
Frequently asked questions
What is the difference between Mailtrap and Postmark?
Mailtrap is an email platform combining safe testing and sandbox environments with production sending capabilities. Postmark is a transactional email service focused on fast, reliable delivery with transparent pricing. Mailtrap is best suited for email testing + qa, while Postmark is geared toward transactional email.
Which is cheaper, Mailtrap or Postmark?
Free tier includes 4,000 emails per month (150/day limit). Paid plans start at $15/month for 10,000 emails with overages at $1.00/1K. 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+. The best value depends on your sending volume. Use the pricing calculator above to compare costs at your expected volume.
Which is faster, Mailtrap or Postmark?
Based on real-world data from Knock, Mailtrap has a median API response time (p50) of 93ms compared to 27ms for Postmark.
Which is more reliable, Mailtrap or Postmark?
From January 22nd to April 22nd, Mailtrap showed an error rate of 0.00% while Postmark showed 0.03%. 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, Mailtrap or Postmark?
On the Knock platform, Mailtrap handled <1M messages from January 22nd to April 22nd compared to 25M–100M for Postmark. Mailtrap volume has remained stable, while Postmark volume has remained stable.
Can I use both Mailtrap and Postmark together?
Yes. Knock enables you to integrate multiple email providers into a single notification workflow. You can use Mailtrap and Postmark 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 Mailtrap vs Postmark?
Mailtrap strengths include strong deliverability with dedicated ips, auto warmup, and automatic authentication and great developer experience with comprehensive docs and mcp support for ides. 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. On the other hand, Mailtrap drawbacks include native integration ecosystem is smaller than established competitors, while Postmark drawbacks include no visual drag-and-drop email editor.
Use either provider with Knock
Knock enables you to integrate Mailtrap, Postmark, or any combination of email providers into a single notification workflow. Manage templates, orchestrate cross-channel delivery, and switch providers without changing your code.