Compare Postmark against SendGrid API performance
Compare real-time performance, reliability, and uptime benchmarks for Postmark and SendGrid, 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) |
|---|---|---|---|---|
 | 10M–25M | 4th of 10 ↓ | 5 | 14 |
 | 100M–500M | 2nd of 10 → | 25 | 25 |
From August 13th to November 11th, Knock routed 10M–25M messages through Postmark and 100M–500M through SendGrid. Postmark reported 14 status page updates over the last 90 days, while SendGrid reported 25.
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: Postmark averaged 59ms compared to 14ms for SendGrid. Postmark's highest daily p50 was 67ms; SendGrid's was 26ms. SendGrid is 45ms 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, Postmark has a p90 of 83ms compared to 33ms for SendGrid. The highest daily p90 was 107ms for Postmark and 37ms for SendGrid. SendGrid handles these slower requests 50ms 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, Postmark reached 241ms at p99 while SendGrid reached 99ms. The highest daily p99 was 1224ms for Postmark and 138ms for SendGrid, indicating the worst-case response time during spikes or provider-side congestion. SendGrid 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 30 | 89 | 0 |
| 0.00% | 0.00% | Aug 13 | 91 | 0 |
Averaged across the date range, Postmark shows a 0.00% daily error rate compared to 0.00% for SendGrid. The highest single-day error rate was 0.01% for Postmark and 0.00% for SendGrid. 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 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.
Recent SendGrid incidents
Recent status page incidents for SendGrid
Ongoing since Dec 23, 2026
THIS IS A SCHEDULED EVENT Dec 22, 20:00 PST - Dec 23, 00:00 PST Nov 6, 10:27 PST Scheduled - Twilio is conducting a planned maintenance from 22 December 2026 at 20:00 PST until 23 December 2026 at 00:00 PST. During the maintenance window, there could be intermittent delays or failures delivering SMS and MMS to and from United States and Canada handsets when sending via subset of long codes, short codes and toll free numbers.
Ongoing since Dec 17, 2026
THIS IS A SCHEDULED EVENT Dec 16, 20:00 PST - Dec 17, 00:00 PST Nov 6, 10:27 PST Scheduled - Twilio is conducting a planned maintenance from 16 December 2026 at 20:00 PST until 17 December 2026 at 00:00 PST. During the maintenance window, there could be intermittent delays or failures delivering SMS and MMS to and from United States and Canada handsets when sending via subset of long codes, short codes and toll free numbers.
Ongoing since Dec 10, 2026
THIS IS A SCHEDULED EVENT Dec 9, 20:00 PST - Dec 10, 00:00 PST Nov 6, 10:26 PST Scheduled - Twilio is conducting a planned maintenance from 09 December 2026 at 20:00 PST until 10 December 2026 at 00:00 PST. During the maintenance window, there could be intermittent delays or failures delivering SMS and MMS to and from United States and Canada handsets when sending via subset of long codes, short codes and toll free numbers.
Ongoing since Dec 3, 2026
THIS IS A SCHEDULED EVENT Dec 2, 20:00 PST - Dec 3, 00:00 PST Nov 6, 10:26 PST Scheduled - Twilio is conducting a planned maintenance from 02 December 2026 at 20:00 PST until 03 December 2026 at 00:00 PST. During the maintenance window, there could be intermittent delays or failures delivering SMS and MMS to and from United States and Canada handsets when sending via subset of long codes, short codes and toll free numbers.
Ongoing since Nov 29, 2026
THIS IS A SCHEDULED EVENT Nov 29, 11:00 - 13:00 PST Oct 29, 03:34 PDT Scheduled - The Globe Telecom network in the Philippines is conducting a planned maintenance from 29 November 2026 at 11:00 PST until 29 November 2026 at 13:00 PST. During the maintenance window, there could be intermittent delays delivering SMS to Globe Telecom Philippines handsets.
Pros and cons
Compare the strengths and tradeoffs between Postmark and SendGrid.
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
SendGrid
Pros
- Comprehensive documentation with SDKs for most major languages
- Rich analytics tools with programmatic API access to engagement data
- Strong focus on deliverability with AI-powered intelligent delivery
- Trusted by Uber, Booking.com, and Yelp for high-volume sending
Cons
- Extended email activity history requires a paid add-on
- Pricing can become complex at higher volumes
- Support response times vary by plan tier
Pricing comparison
Compare Postmark and SendGrid as your email volume grows.
Frequently asked questions
Postmark is a transactional email service focused on fast, reliable delivery with transparent pricing. SendGrid is a cloud-based email delivery platform owned by Twilio, known for high-volume transactional and marketing email. Postmark is best suited for transactional email, while SendGrid is geared toward high-volume transactional + marketing.
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. Free tier includes up to 100 emails per day for 60 days. Paid plans start at $19.95/month for 50,000 emails on the Essentials plan, with an Essentials 100K tier at $34.95/month. Pro plans with dedicated IPs start at $249/month for 300,000 emails. 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, Postmark has a median API response time (p50) of 59ms compared to 14ms for SendGrid.
From August 13th to November 11th, Postmark showed an error rate of 0.00% while SendGrid 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, Postmark handled 10M–25M messages from August 13th to November 11th compared to 100M–500M for SendGrid. Postmark is currently seeing declining volume, while SendGrid volume has remained stable.
Yes. Knock enables you to integrate multiple email providers into a single notification workflow. You can use Postmark and SendGrid side by side, route traffic between them, or migrate from one to the other without changing your application code.
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. SendGrid strengths include comprehensive documentation with sdks for most major languages and rich analytics tools with programmatic api access to engagement data. On the other hand, Postmark drawbacks include no visual drag-and-drop email editor, while SendGrid drawbacks include extended email activity history requires a paid add-on.