Mailgun vs Postmark
Compare Mailgun 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) |
|---|---|---|---|---|
| 100M–500M | 5th of 10 → | 5 | 14 |
| 1M–10M | 4th of 10 ↓ | 5 | 10 |
From June 3rd to August 31st, Knock routed 100M–500M messages through Mailgun and 1M–10M through Postmark. Mailgun reported 14 status page updates over the last 90 days, while Postmark reported 10.
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 June 3rd to August 31st. The top-line number is an average of these daily values: Mailgun averaged 119ms compared to 60ms for Postmark. Mailgun's highest daily p50 was 130ms; Postmark's was 209ms. Postmark is 59ms 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 212ms for Postmark. The highest daily p90 was 197ms for Mailgun and 582ms for Postmark. Mailgun handles these slower requests 42ms 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 215ms at p99 while Postmark reached 559ms. The highest daily p99 was 432ms for Mailgun and 1224ms for Postmark, indicating the worst-case response time during spikes or provider-side congestion. Mailgun 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 27 | 89 | 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 Aug 31, 2026 — Resolved Aug 31, 2026
Aug 31, 15:01 PDT Resolved - Event queues have caught up and events are processing normally. Aug 31, 14:28 PDT Update - The event processing backlog is steadily decreasing, and we’re continuing to monitor the recovery. We expect all delays to be resolved within the hour. Aug 31, 13:43 PDT Update - The event processing backlog is steadily decreasing, and we’re continuing to monitor the recovery. Aug 31, 13:13 PDT Update - The event processing backlog is steadily decreasing, and we’re co
Started Aug 27, 2026 — Resolved Aug 27, 2026
Aug 27, 14:16 PDT Resolved - This incident has been resolved. Aug 27, 14:00 PDT Monitoring - A fix has been implemented and we are monitoring the results. Aug 27, 13:45 PDT Identified - We have identified the issue and working on restoring service. Aug 27, 13:38 PDT Investigating - We are currently investigating an outage in our EU datacenter
Started Aug 20, 2026 — Resolved Aug 20, 2026
Aug 20, 10:31 PDT Resolved - This incident has been resolved. Aug 20, 10:09 PDT Update - GCP has put a mitigation in place, we are monitoring the results. At this time we are experiencing no impacts. All delayed webhooks and logs have been processed. Aug 20, 09:30 PDT Update - Outbound delivery is operating normally. Currently there are delays for event logs and some webhooks. Aug 20, 09:19 PDT Monitoring - Mailgun is monitoring service impacts in GCP's us-west1 region. We are routing
Started Aug 17, 2026 — Resolved Aug 17, 2026
Aug 17, 13:18 PDT Resolved - We have received confirmation that an external issue impacting email delivery to Microsoft 365 domains has been resolved. Impacted messages would have received an error stating "5.7.511 Access denied, banned sender" between Friday, August 14th and Monday, August 17th. Any failed messages will need to be resent. Information on retrying messages can be found in our Help Center here: https://help.mailgun.com/hc/en-us/articles/18596982041883-Resending-messages
Started Aug 11, 2026 — Resolved Aug 11, 2026
Aug 11, 00:07 PDT Resolved - This incident has been resolved. Aug 10, 23:54 PDT Monitoring - A fix has been implemented and we are monitoring the results. Aug 10, 22:32 PDT Identified - The issue has been identified and a fix is being implemented. Aug 10, 22:32 PDT Investigating - We are currently experiencing a denial of service attack against our click and open tracking servers in our US regions. Remediation work is underway. Some requests may time out or fail at this time.
Recent Postmark incidents
Recent status page incidents for Postmark
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.
Started Aug 18, 2026 — Resolved Aug 19, 2026
The issue is now fully resolved. We are continuing to improve our systems, observability, and monitoring to prevent future occurrences. Thank you for your patience. Starting August 18th at ~9:34am CT (~14:34 UTC), Postmark experienced delays in delivering open webhook events. New open events resumed delivery on August 19th at ~8:47am CT (~13:47 UTC), and all backlogged events completed re-delivery at ~4:52pm CT (~21:52 UTC).
Started Aug 18, 2026 — Resolved Aug 18, 2026
The maintenance is now complete. Thanks for your patience.
Started Aug 14, 2026 — Resolved Aug 15, 2026
The issue has been resolved after additional monitoring into the early morning. Thank you for your patience.
Started Aug 7, 2026 — Resolved Aug 7, 2026
The maintenance is now complete. Thanks for your patience.
Pros and cons
Mailgun
Postmark
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
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
- Requires familiarity with email protocols and API integrations
- Pricing tiers can be confusing
- Email template features are basic without the Mailjet editor
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 Mailgun and Postmark?
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.
Which is cheaper, Mailgun or Postmark?
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 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, Mailgun or Postmark?
Based on real-world data from Knock, Mailgun has a median API response time (p50) of 119ms compared to 60ms for Postmark.
Which is more reliable, Mailgun or Postmark?
From June 3rd to August 31st, 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.
Which is more popular, Mailgun or Postmark?
On the Knock platform, Mailgun handled 100M–500M messages from June 3rd to August 31st compared to 1M–10M for Postmark. Mailgun volume has remained stable, while Postmark is seeing declining volume.
Can I use both Mailgun and Postmark together?
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.
What are the main pros and cons of Mailgun vs Postmark?
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.
Use either provider with Knock
Knock enables you to integrate Mailgun, 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.