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 ↑ | 0 | 0 |
| 500M+ | 2nd of 10 → | 5 | 25 |
From March 24th to June 22nd, Knock routed 25M–100M messages through Postmark and 500M+ through SendGrid. Postmark reported 0 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 March 24th to June 22nd. The top-line number is an average of these daily values: Postmark averaged 7ms compared to 23ms for SendGrid. Postmark's highest daily p50 was 57ms; SendGrid's was 25ms. Postmark is 16ms 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 75ms compared to 77ms for SendGrid. The highest daily p90 was 143ms for Postmark and 86ms 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 184ms at p99 while SendGrid reached 346ms. The highest daily p99 was 38235ms for Postmark and 2501ms for SendGrid, indicating the worst-case response time during spikes or provider-side congestion. Postmark 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% |
|---|---|---|---|---|---|
| 0.02% | 2.37% | Mar 27 | 86 | 2 |
| 0.00% | 0.04% | Mar 24 | 89 | 2 |
Averaged across the date range, Postmark shows a 0.02% daily error rate compared to 0.00% for SendGrid. The highest single-day error rate was 2.37% for Postmark and 0.04% 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
No incidents reported in the last 90 days
Recent SendGrid incidents
Recent status page incidents for SendGrid
Started Jun 14, 2026 — Resolved Jun 14, 2026
Jun 14, 14:00 PDT Resolved - Twilio-Sendgrid mail delivery was degraded for approximately 16 minutes between 3:18 PM and 3:34 PM Pacific Time on 06/14/2026. During this period of time customers may have experienced delays affecting a subset of users. User experience was degraded with delayed mail delivery during this window, though the scope was limited to affected users rather than a system-wide outage. The issue has now been resolved.
Started Jun 14, 2026 — Resolved Jun 14, 2026
Jun 14, 12:23 PDT Resolved - Our engineers have monitored the fix and confirmed the issue with high latency and 5xx errors has been resolved. All services are now operating normally at this time. Jun 14, 11:11 PDT Monitoring - Our engineers have implemented a fix and are monitoring system performance. We will continue to observe the platform for the next hour to ensure full stability, and will mark this incident as resolved if no further issues are seen. We will provide another update in 1 h
Started Jun 11, 2026 — Resolved Jun 11, 2026
Jun 11, 10:05 PDT Resolved - Twilio-Sengrid mail delivery was degraded for approximately 9 minutes between 9:18 AM and 9:27AM Pacific Time on 06/11/2026. During this period of time customers may have experienced delays affecting a subset of users. User experience was degraded with delayed mail delivery during this window, though the scope was limited to affected users rather than system-wide outage. The issue has now been resolved.
Started Jun 10, 2026 — Resolved Jun 10, 2026
Jun 10, 01:49 PDT Resolved - Our engineers have monitored the fix and confirmed the issue with email deferrals has been resolved. All services are now operating normally at this time. Jun 9, 22:51 PDT Monitoring - Our engineers have implemented a fix and are monitoring system performance. We will provide another update in an hour or as soon as more information becomes available. Jun 9, 22:07 PDT Investigating - Starting around 9:25 AM GMT+8 on June 10, 2026, our engineers began investig
Started May 29, 2026 — Resolved May 29, 2026
May 29, 07:30 PDT Resolved - Customers have experienced elevated latency occurring in US East region from 6:30 AM to 8:58 AM Pacific time. Our engineers have investigated and resolved the issue. All impacted services are operating normally.
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 7ms compared to 23ms for SendGrid.
Which is more reliable, Postmark or SendGrid?
From March 24th to June 22nd, Postmark showed an error rate of 0.02% 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 March 24th to June 22nd compared to 500M+ for SendGrid. Postmark is currently trending upward in adoption, 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.