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 ↓ | 1 | 7 |
| 500M+ | 2nd of 10 → | 9 | 24 |
From April 17th to July 16th, Knock routed 25M–100M messages through Postmark and 500M+ through SendGrid. Postmark reported 7 status page updates over the last 90 days, while SendGrid reported 24.
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 April 17th to July 16th. The top-line number is an average of these daily values: Postmark averaged 4ms compared to 22ms for SendGrid. Postmark's highest daily p50 was 60ms; SendGrid's was 31ms. Postmark is 18ms 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 76ms compared to 78ms for SendGrid. The highest daily p90 was 220ms for Postmark and 88ms 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 247ms at p99 while SendGrid reached 278ms. The highest daily p99 was 1429ms for Postmark and 1833ms 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% |
|---|---|---|---|---|---|
| 0.00% | 0.04% | Jul 9 | 84 | 4 |
| 0.00% | 0.02% | May 8 | 90 | 1 |
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 0.04% for Postmark and 0.02% 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 Jul 6, 2026 — Resolved Jul 7, 2026
We've now resolved the incident. Thanks for your patience.
Started Jun 11, 2026 — Resolved Jun 12, 2026
All previously backlogged events have been processed. The issue occurred starting on June 11th at approximately 3:36am to June 12th 1:01pm CT (June 11th 08:36 – June 12th 18:01 UTC). Thank you for your patience. We will continue to improve our systems.
Started Jun 4, 2026 — Resolved Jun 5, 2026
The backlog of messages have been sent and system performance has returned to its expected state. Sending delays occurred between 4:50 – 6:35pm CT (21:50 – 23:35 UTC) for both transactional and broadcast mail. Engineering will continue to monitor.
Started Jun 1, 2026 — Resolved Jun 2, 2026
The issue has been resolved. Thank for your patience.
Started May 28, 2026 — Resolved May 28, 2026
The issue has been resolved.
Recent SendGrid incidents
Recent status page incidents for SendGrid
Ongoing since Jul 29, 2026
THIS IS A SCHEDULED EVENT Jul 29, 09:00 - 12:00 PDT Jul 9, 05:10 PDT Scheduled - On July 29, 2026 at 9:00 AM PT (originally planned for July 22), SendGrid incident and maintenance notifications will move to the Twilio Status Page: https://status.twilio.com. Your existing SendGrid Status Page subscription will be migrated. Depending on how you currently receive notifications, you may need to confirm your subscription to continue receiving updates. What to expect: EMAIL SUBSCRIBERS: You shou
Started Jul 16, 2026 — Resolved Jul 16, 2026
Jul 16, 11:15 PDT Resolved - Our engineers have monitored the fix and confirmed the issue with delay with account actions has been resolved. All services are now operating normally at this time. Jul 15, 20:12 PDT Monitoring - Our engineers have implemented a fix and are monitoring system performance. We will provide another update as soon as more information becomes available. Jul 15, 18:58 PDT Update - Our engineers are still investigating an issue with account actions. Users may experi
Started Jul 14, 2026 — Resolved Jul 14, 2026
Jul 14, 10:50 PDT Resolved - Our engineers have investigated and resolved the issues with email delays that involved a certain subset of users. From 10:20 AM PST to 10:25 AM PST customers may have experienced delays with email deliverability for a certain subset of users. This would have impacted Email API and Marketing mail sending. There was no data loss due to this incident. The issue has been resolved and all impacted services are operating normally.
Started Jul 13, 2026 — Resolved Jul 13, 2026
Jul 13, 10:15 PDT Resolved - Our engineers have monitored the fix and confirmed the issue with account actions has been resolved. All services are now operating normally at this time. Jul 13, 09:36 PDT Monitoring - Our engineers have implemented a fix and are monitoring system performance. Account actions, such as password resets, are beginning to process as the system recovers and clears any remaining delays. As a reminder, this issue continues to have no impact on mail send. We will provid
Started Jul 11, 2026 — Resolved Jul 11, 2026
Jul 11, 13:35 PDT Resolved - Our engineers have monitored the fix and confirmed the issue has been resolved. All services are now operating normally at this time. Jul 11, 13:07 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. Jul 11, 12:23 PDT Identified - Our engineers have identified the issue and are working toward a fix. We will provide another update
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 4ms compared to 22ms for SendGrid.
Which is more reliable, Postmark or SendGrid?
From April 17th to July 16th, 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.
Which is more popular, Postmark or SendGrid?
On the Knock platform, Postmark handled 25M–100M messages from April 17th to July 16th compared to 500M+ for SendGrid. Postmark is currently seeing declining volume, 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.