Postmark vs SendGrid
Compare Postmark and SendGrid 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) |
|---|---|---|---|---|
| 25M–100M | 4th of 10 → | 5 | 11 |
| 500M+ | 2nd of 10 → | 25 | 25 |
From May 30th to August 28th, Knock routed 25M–100M messages through Postmark and 500M+ through SendGrid. Postmark reported 11 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 May 30th to August 28th. The top-line number is an average of these daily values: Postmark averaged 15ms compared to 21ms for SendGrid. Postmark's highest daily p50 was 62ms; SendGrid's was 36ms. Both providers deliver comparable response times for the typical request.
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 85ms compared to 76ms for SendGrid. The highest daily p90 was 222ms for Postmark and 89ms for SendGrid. Both providers show similar performance at this percentile, indicating comparable consistency.
The 99th percentile (p99) represents the long tail — the slowest 1% of requests. Averaged across all days, Postmark reached 560ms at p99 while SendGrid reached 230ms. The highest daily p99 was 19244ms for Postmark and 1758ms 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% |
|---|---|---|---|---|---|
| 0.01% | 0.40% | Aug 25 | 68 | 19 |
| 0.00% | 0.00% | May 30 | 91 | 0 |
Averaged across the date range, Postmark shows a 0.01% daily error rate compared to 0.00% for SendGrid. The highest single-day error rate was 0.40% 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 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.
Recent SendGrid incidents
Recent status page incidents for SendGrid
Ongoing since Oct 16, 2026
THIS IS A SCHEDULED EVENT Oct 16, 14:00 - 22:00 PDT Jul 29, 00:27 PDT Scheduled - Twilio will perform scheduled network maintenance in our IE1 region during an 8-hour window from 16 October 2026 at 14:00 PDT to 16 October 2026 at 22:00 PDT. During this window, customers may experience a brief service interruption of up to 90 seconds affecting the following: Interconnected Customers: All IE1 interconnected customers will experience a brief interconnection service interruption of up to 90 seco
Ongoing since Oct 1, 2026
THIS IS A SCHEDULED EVENT Sep 30, 20:00 PDT - Oct 1, 00:00 PDT Aug 12, 11:57 PDT Scheduled - Twilio is conducting a planned maintenance from 30 September 2026 at 20:00 PDT until 01 October 2026 at 00:00 PDT. During the maintenance window, there could be intermittent delays or failures delivering SMS and MMS to and from United States and Canada handsets via subset of long codes, short codes and toll free numbers.
Ongoing since Sep 24, 2026
THIS IS A SCHEDULED EVENT Sep 23, 20:00 PDT - Sep 24, 00:00 PDT Aug 12, 11:57 PDT Scheduled - Twilio is conducting a planned maintenance from 23 September 2026 at 20:00 PDT until 24 September 2026 at 00:00 PDT. During the maintenance window, there could be intermittent delays or failures delivering SMS and MMS to and from United States and Canada handsets via subset of long codes, short codes and toll free numbers.
Ongoing since Sep 22, 2026
THIS IS A SCHEDULED EVENT Sep 22, 15:00 - 21:00 PDT Aug 24, 23:50 PDT Scheduled - Our Voice carrier partner in the Czech Republic is conducting a planned maintenance from 22 September 2026 at 15:00 PDT until 22 September 2026 at 21:00 PDT. During the maintenance window, there could be intermittent call disconnects or call failures from and to Twilio Czech Republic phone numbers.
Ongoing since Sep 21, 2026
THIS IS A SCHEDULED EVENT Sep 21, 15:00 - 21:00 PDT Aug 24, 23:49 PDT Scheduled - Our Voice carrier partner in the Czech Republic is conducting a planned maintenance from 21 September 2026 at 15:00 PDT until 21 September 2026 at 21:00 PDT. During the maintenance window, there could be intermittent call disconnects or call failures from and to Twilio Czech Republic phone numbers.
Pros and cons
Postmark
SendGrid
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
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
- No visual drag-and-drop email editor
- Less suited for high-volume marketing email
- Smaller feature set compared to all-in-one platforms
Cons
- Extended email activity history requires a paid add-on
- Pricing can become complex at higher volumes
- Support response times vary by plan tier
Frequently asked questions
What is the difference between Postmark and SendGrid?
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.
Which is cheaper, Postmark or SendGrid?
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+. 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.
Which is faster, Postmark or SendGrid?
Based on real-world data from Knock, Postmark has a median API response time (p50) of 15ms compared to 21ms for SendGrid.
Which is more reliable, Postmark or SendGrid?
From May 30th to August 28th, Postmark showed an error rate of 0.01% 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.
Which is more popular, Postmark or SendGrid?
On the Knock platform, Postmark handled 25M–100M messages from May 30th to August 28th compared to 500M+ for SendGrid. Postmark volume has remained stable, while SendGrid volume has remained stable.
Can I use both Postmark and SendGrid together?
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.
What are the main pros and cons of Postmark vs SendGrid?
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.
Use either provider with Knock
Knock enables you to integrate Postmark, SendGrid, or any combination of email providers into a single notification workflow. Manage templates, orchestrate cross-channel delivery, and switch providers without changing your code.