Amazon SES vs Postmark
Compare Amazon SES 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 | 3rd of 10 → | 0 | 0 |
| 1M–10M | 4th of 10 ↓ | 4 | 12 |
From July 4th to October 2nd, Knock routed 100M–500M messages through Amazon SES and 1M–10M through Postmark. Amazon SES reported 0 status page updates over the last 90 days, while Postmark reported 12.
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.
| Provider | Median (p50) | p90 | p95 | p99 |
|---|---|---|---|---|
| 163ms | 242ms | 309ms | 426ms |
| 62ms | 209ms | 227ms | 408ms |
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: Amazon SES averaged 163ms compared to 62ms for Postmark. Amazon SES's highest daily p50 was 216ms; Postmark's was 209ms. Postmark is 101ms 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, Amazon SES has a p90 of 242ms compared to 209ms for Postmark. The highest daily p90 was 312ms for Amazon SES and 250ms for Postmark. Postmark handles these slower requests 33ms 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, Amazon SES reached 426ms at p99 while Postmark reached 408ms. The highest daily p99 was 507ms for Amazon SES 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% | 0.00% | Jul 4 | 91 | 0 |
| 0.00% | 0.01% | Aug 30 | 89 | 0 |
Averaged across the date range, Amazon SES shows a 0.00% daily error rate compared to 0.00% for Postmark. The highest single-day error rate was 0.00% for Amazon SES 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 Amazon SES incidents
Recent status page incidents for Amazon SES
No incidents reported in the last 90 days
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.
Pros and cons
Amazon SES
Postmark
Pros
- Delivers billions of emails per year for Netflix, Reddit, and Amazon
- Lowest cost per email among major providers with simple pay-as-you-go pricing
- Deep integration with the AWS ecosystem and SDKs in all major languages
- Highly scalable with no sending limits after warmup
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
- Setup is complex with documentation that can be difficult to navigate
- New accounts are sandboxed to 200 messages per 24-hour period
- Accessing analytics requires additional AWS services like SNS and Lambda
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 Amazon SES and Postmark?
Amazon SES is a cost-effective, cloud-scale email service built on AWS infrastructure. Postmark is a transactional email service focused on fast, reliable delivery with transparent pricing. Amazon SES is best suited for cost-sensitive, high-volume, while Postmark is geared toward transactional email.
Which is cheaper, Amazon SES or Postmark?
3,000 free emails per month for the first 12 months. After that, $0.10 per 1,000 emails with additional charges for attachments and dedicated IPs. 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, Amazon SES or Postmark?
Based on real-world data from Knock, Amazon SES has a median API response time (p50) of 163ms compared to 62ms for Postmark.
Which is more reliable, Amazon SES or Postmark?
From July 4th to October 2nd, Amazon SES 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, Amazon SES or Postmark?
On the Knock platform, Amazon SES handled 100M–500M messages from July 4th to October 2nd compared to 1M–10M for Postmark. Amazon SES volume has remained stable, while Postmark is seeing declining volume.
Can I use both Amazon SES and Postmark together?
Yes. Knock enables you to integrate multiple email providers into a single notification workflow. You can use Amazon SES 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 Amazon SES vs Postmark?
Amazon SES strengths include delivers billions of emails per year for netflix, reddit, and amazon and lowest cost per email among major providers with simple pay-as-you-go pricing. 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, Amazon SES drawbacks include setup is complex with documentation that can be difficult to navigate, while Postmark drawbacks include no visual drag-and-drop email editor.
Use either provider with Knock
Knock enables you to integrate Amazon SES, 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.