Compare Mailjet against Postmark API performance
Compare real-time performance, reliability, and uptime benchmarks for Mailjet and Postmark, powered by proprietary data from billions of messages sent through Knock.
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 | 6th of 10 → | 0 | 2 |
 | 10M–25M | 4th of 10 ↓ | 5 | 14 |
From August 13th to November 11th, Knock routed <1M messages through Mailjet and 10M–25M through Postmark. Mailjet reported 2 status page updates over the last 90 days, while Postmark reported 14.
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 August 13th to November 11th. The top-line number is an average of these daily values: Mailjet averaged 406ms compared to 59ms for Postmark. Mailjet's highest daily p50 was 446ms; Postmark's was 67ms. Postmark is 347ms 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, Mailjet has a p90 of 594ms compared to 83ms for Postmark. The highest daily p90 was 1020ms for Mailjet and 107ms for Postmark. Postmark handles these slower requests 511ms 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, Mailjet reached 746ms at p99 while Postmark reached 241ms. The highest daily p99 was 2503ms for Mailjet and 1224ms 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% | Aug 13 | 91 | 0 |
| 0.00% | 0.01% | Aug 30 | 89 | 0 |
Averaged across the date range, Mailjet shows a 0.00% daily error rate compared to 0.00% for Postmark. The highest single-day error rate was 0.00% for Mailjet and 0.01% 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 Mailjet incidents
Recent status page incidents for Mailjet
Started Sep 23, 2026 — Resolved Sep 23, 2026
Sep 23, 05:00 UTC Completed - The scheduled maintenance has been completed. Sep 23, 04:00 UTC In progress - Scheduled maintenance is currently in progress. We will provide updates as necessary. Sep 15, 08:10 UTC Scheduled - We’ll be performing scheduled infrastructure maintenance on Wednesday, September 23, starting at 4:00 AM UTC. The estimated impact duration is 30 minutes. During this window, you won't be able to log in or send new messages via SMTP or API. Don't worry, any emails alr
Started Sep 4, 2026 — Resolved Sep 4, 2026
Sep 4, 12:55 UTC Resolved - This incident has been resolved. Sep 4, 12:23 UTC Monitoring - Starting around 08:00 UTC, Microsoft began experiencing an incident causing an increased volume of deferred emails across all M365 regions. The affected responses are returning "451 4.7.500 Server busy". Our teams are actively monitoring the situation. Sending to other email providers is not affected.
Recent Postmark incidents
Recent status page incidents for Postmark
Started Nov 5, 2026 — Resolved Nov 5, 2026
Latency around activity data looks to be back to normal. We will continue to monitor. Thanks for your patience.
Started Nov 4, 2026 — Resolved Nov 5, 2026
The maintenance is now complete. Thanks for your patience.
Started Nov 4, 2026 — Resolved Nov 4, 2026
Inbound processing is back to normal. The fix is holding, and all delayed messages have been delivered to your webhooks. We'll keep monitoring to make sure it stays that way.
Started Nov 3, 2026 — Resolved Nov 4, 2026
The maintenance is now complete. That took a lot longer than expected... we are going to schedule another maintenance window starting tomorrow, November 4th at 3PM Eastern.
Started Oct 27, 2026 — Resolved Oct 27, 2026
Resolved We've identified and resolved the issue affecting SMS two-factor authentication codes. Codes should now arrive as expected when you log in to your Postmark account. Sending email through Postmark wasn't affected. If you still don't receive a code, please contact support: https://postmarkapp.com/support Resolved at 14:50 EDT (18:50 UTC) - 27 October 2026.
Pros and cons
Compare the strengths and tradeoffs between Mailjet and Postmark.
Mailjet
Pros
- Hybrid support for both marketers and developers in a single platform
- Unique real-time collaboration features for team-based template editing
- EU-only data processing for companies with strict data residency requirements
- Powers email delivery for over 130,000 companies including Microsoft and DHL
Cons
- Activated automation workflows cannot be edited, requiring new workflows for any changes
- Some analytics and deliverability tools are locked behind higher pricing plans
- Deliverability can lag behind specialists like Postmark
Postmark
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
- No visual drag-and-drop email editor
- Less suited for high-volume marketing email
- Smaller feature set compared to all-in-one platforms
Pricing comparison
Compare Mailjet and Postmark as your email volume grows.
Frequently asked questions
Mailjet is a collaborative email platform with real-time editing and combined transactional and marketing capabilities. Postmark is a transactional email service focused on fast, reliable delivery with transparent pricing. Mailjet is best suited for team collaboration + marketing, while Postmark is geared toward transactional email.
Free tier includes 200 emails per day (6,000/month). Paid plans start at $17/month for 15,000 emails with no daily limit. Premium plans start at $105/month for 100,000 emails. Free tier includes 100 emails per month. Paid plans start at $15/month for 10,000 emails on Basic, $16.50/month on Pro, and $18/month on Platform. Published pricing ends at 1.5 million emails per month. The best value depends on your sending volume. Use the pricing calculator above to compare costs at your expected volume.
Based on real-world data from Knock, Mailjet has a median API response time (p50) of 406ms compared to 59ms for Postmark.
From August 13th to November 11th, Mailjet showed an error rate of 0.00% while Postmark 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.
On the Knock platform, Mailjet handled <1M messages from August 13th to November 11th compared to 10M–25M for Postmark. Mailjet volume has remained stable, while Postmark is seeing declining volume.
Yes. Knock enables you to integrate multiple email providers into a single notification workflow. You can use Mailjet and Postmark side by side, route traffic between them, or migrate from one to the other without changing your application code.
Mailjet strengths include hybrid support for both marketers and developers in a single platform and unique real-time collaboration features for team-based template editing. 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, Mailjet drawbacks include activated automation workflows cannot be edited, requiring new workflows for any changes, while Postmark drawbacks include no visual drag-and-drop email editor.