Compare Mailgun against Postmark API performance
Compare real-time performance, reliability, and uptime benchmarks for Mailgun 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) |
|---|---|---|---|---|
 | 100M–500M | 5th of 10 → | 1 | 9 |
 | 10M–25M | 4th of 10 ↓ | 5 | 14 |
From August 13th to November 11th, Knock routed 100M–500M messages through Mailgun and 10M–25M through Postmark. Mailgun reported 9 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: Mailgun averaged 121ms compared to 59ms for Postmark. Mailgun's highest daily p50 was 133ms; Postmark's was 67ms. Postmark is 62ms 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, Mailgun has a p90 of 170ms compared to 83ms for Postmark. The highest daily p90 was 197ms for Mailgun and 107ms for Postmark. Postmark handles these slower requests 87ms 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, Mailgun reached 225ms at p99 while Postmark reached 241ms. The highest daily p99 was 506ms for Mailgun and 1224ms for Postmark, indicating the worst-case response time during spikes or provider-side congestion. Both providers exhibit comparable tail response times, meaning neither is significantly more prone to outlier slowdowns.
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 27 | 90 | 0 |
| 0.00% | 0.01% | Aug 30 | 89 | 0 |
Averaged across the date range, Mailgun shows a 0.00% daily error rate compared to 0.00% for Postmark. The highest single-day error rate was 0.01% for Mailgun 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 Mailgun incidents
Recent status page incidents for Mailgun
Started Oct 28, 2026 — Resolved Oct 28, 2026
Oct 28, 02:40 PDT Resolved - This incident has been resolved. Oct 28, 02:27 PDT Monitoring - A fix has been implemented and we are monitoring the results. Oct 28, 01:54 PDT Identified - The issue has been identified and a fix is being implemented. Oct 28, 01:36 PDT Investigating - We are currently investigating this issue.
Started Sep 30, 2026 — Resolved Sep 30, 2026
Sep 30, 02:58 PDT Resolved - This incident has been resolved. Sep 30, 02:48 PDT Monitoring - A fix has been implemented and we are monitoring the results. Sep 30, 02:38 PDT Identified - The issue has been identified and a fix is being implemented. Sep 30, 02:16 PDT Investigating - We are currently investigating this issue.
Started Sep 14, 2026 — Resolved Sep 14, 2026
Sep 14, 03:13 PDT Resolved - This incident has been resolved. Sep 14, 02:55 PDT Monitoring - A fix has been implemented and we are monitoring the results. Sep 14, 02:15 PDT Investigating - We are currently investigating this issue.
Started Sep 4, 2026 — Resolved Sep 4, 2026
Sep 4, 07:33 PDT Resolved - This incident has been resolved. Sep 4, 07:21 PDT Monitoring - A fix has been implemented and we are monitoring the results. Sep 4, 07:16 PDT Investigating - We are currently investigating this issue.
Started Sep 4, 2026 — Resolved Sep 4, 2026
Sep 4, 05:54 PDT Resolved - Microsoft has resolved the underlying issue, we are seeing deliveries to M365 process normally. Sep 4, 05:22 PDT Update - We are continuing to monitor for any further issues. Sep 4, 05:20 PDT 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. Send
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 Mailgun and Postmark.
Mailgun
Pros
- Well-written documentation with comprehensive guides and best practices for deliverability
- Robust deliverability support with optional expert pairing to optimize sending
- Powerful inbound email processing with customizable routing rules
- Trusted by Lyft, American Express, and Wikipedia since 2010
Cons
- Requires familiarity with email protocols and API integrations
- Pricing tiers can be confusing
- Email template features are basic without the Mailjet editor
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 Mailgun and Postmark as your email volume grows.
Frequently asked questions
Mailgun is a developer-focused email API platform owned by Sinch, known for flexible sending and receiving capabilities. Postmark is a transactional email service focused on fast, reliable delivery with transparent pricing. Mailgun is best suited for developer-focused sending + receiving, while Postmark is geared toward transactional email.
Free tier includes 100 emails per day with no expiration. Paid plans start at $15/month for 10,000 emails with overages at $1.80/1K. 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, Mailgun has a median API response time (p50) of 121ms compared to 59ms for Postmark.
From August 13th to November 11th, Mailgun 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, Mailgun handled 100M–500M messages from August 13th to November 11th compared to 10M–25M for Postmark. Mailgun 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 Mailgun and Postmark side by side, route traffic between them, or migrate from one to the other without changing your application code.
Mailgun strengths include well-written documentation with comprehensive guides and best practices for deliverability and robust deliverability support with optional expert pairing to optimize sending. 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, Mailgun drawbacks include requires familiarity with email protocols and api integrations, while Postmark drawbacks include no visual drag-and-drop email editor.