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 | 10 |
 | 500M+ | 2nd of 10 → | 13 | 23 |
From December 12th to March 12th, Knock routed 25M–100M messages through Postmark and 500M+ through SendGrid. Postmark reported 10 status page updates over the last 90 days, while SendGrid reported 23.
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 December 12th to March 12th. The top-line number is an average of these daily values: Postmark averaged 33ms compared to 22ms for SendGrid. Postmark's highest daily p50 was 57ms; SendGrid's was 28ms. SendGrid is 11ms 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 91ms compared to 77ms for SendGrid. The highest daily p90 was 112ms for Postmark and 98ms 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 208ms at p99 while SendGrid reached 159ms. The highest daily p99 was 648ms for Postmark and 1256ms 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% | 0.07% | Feb 4 | 85 | 4 |
| 0.00% | 0.02% | Jan 21 | 83 | 3 |
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 0.07% 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
Status page incidents from the last 30 days for Postmark
Started Mar 8, 2026 — Resolved Mar 8, 2026
Resolved! Thank you for your patience.
Started Mar 4, 2026 — Resolved Mar 4, 2026
We've now resolved the incident. Thanks for your patience.
Started Feb 26, 2026 — Resolved Feb 27, 2026
The incident has been resolved. Engineering will continue to monitor through the weekend. Long term system improvements and mitigation processes will continue to be a high priority effort. We appreciate and thank you for your patience.
Started Feb 23, 2026 — Resolved Feb 23, 2026
We've now resolved the incident. Thanks for your patience.
Started Feb 11, 2026 — Resolved Feb 12, 2026
We've resolved the issue. Thanks for your patience.
Recent SendGrid incidents
Status page incidents from the last 30 days for SendGrid
Started Mar 11, 2026 — Resolved Mar 11, 2026
Mar 10, 18:00 PDT Completed - The scheduled maintenance has been completed.Mar 10, 17:30 PDT In progress - Scheduled maintenance is currently in progress. We will provide updates as necessary.Mar 9, 07:16 PDT Scheduled - As part of correcting an inaccurate timestamp in the response from our Spamreport API request, we will be performing database maintenance on March 10th, from 5:30 to 6:00pm PT. During this time, customers will be unable to access the public API and v2 equivalent APIs and all Sp
Started Mar 8, 2026 — Resolved Mar 8, 2026
Mar 7, 20:00 PST Completed - The scheduled maintenance has been completed.Mar 7, 16:00 PST In progress - Scheduled maintenance is currently in progress. We will provide updates as necessary.Feb 27, 14:47 PST Scheduled - In order to increase the stability and scalability of our systems, we are performing scheduled maintenance on our infrastructure on Saturday, March 7th, from 4PM-8PM PDT. During this time, customers may not be able to create new accounts, users, subusers, teammates, or API keys
Started Mar 7, 2026 — Resolved Mar 7, 2026
Mar 6, 18:13 PST Completed - The scheduled maintenance has been completed.Feb 23, 10:23 PST Update - Scheduled maintenance is still in progress. We will provide updates as necessary.Feb 23, 10:02 PST Update - From Monday February 23rd - Friday March 6th, our legacy webhook infrastructure will be disabled for 12 hours daily, then re-enabled, affecting webhook deliveries.Feb 18, 12:04 PST Update - Scheduled maintenance is still in progress. We will provide updates as necessary.Feb 17, 14:36 PST U
Started Mar 5, 2026 — Resolved Mar 5, 2026
Mar 5, 11:14 PST Resolved - Between 8:53 AM and 9:37 AM PST, customers may have experienced delays in email event processing, including click and open data. Our Engineers identified a bottleneck, and have resolved the issue. While email delivery continued with low execution times, the reporting of these events to the Stats API and your dashboard was delayed. However, all downstream queues, including Engagement Stats, have fully caught up as of 9:45 AM PST and are resolved at the time.
Started Mar 4, 2026 — Resolved Mar 4, 2026
Mar 4, 08:44 PST Resolved - Our engineers have investigated and resolved an issue that occurred causing delays in timezone updates. On 03/03 ~2:09PM customers would have seen errors in the console when trying to update their timezone setting or while fetching timezones via /v3/timezones. A fix was deployed a fix on 03/04 ~7:48AM. This issuse has now been resolved
Started Mar 4, 2026 — Resolved Mar 4, 2026
Mar 4, 07:30 PST Resolved - Our engineers have investigated and resolved the issues that began on 3/4/2026 from 8am PST to 3/9/2026 at 5pm PST that impacted the reporting for a subset of group unsubscribe and group resubscribe Event Webhooks. Users may have experienced issues with group unsubscribes and group resubscribes that were not processed, although the api calls for those events were processed. The issue has been resolved and all impacted services are operating normally.
Started Mar 3, 2026 — Resolved Mar 3, 2026
Mar 2, 17:17 PST Resolved - Between 4:00 PM and 5:04 PM PST, customers may have experienced delays when viewing Global Stats. Our Engineers identified and resolved the issue
Started Mar 3, 2026 — Resolved Mar 3, 2026
Mar 2, 17:05 PST Resolved - Between 4:00pm to 4:30pm PT, some mail delivery were delayed. There was no data loss or API unavailability. Our Engineers identified and resolved the issue.
Started Mar 2, 2026 — Resolved Mar 2, 2026
Mar 2, 11:06 PST Resolved - Our engineers have confirmed this issue is now resolved. Customers in Argentina should now be able to authenticate and add credit cards successfully. If you are located in Argentina and are still experiencing issues adding or authenticating a credit card, please reach out to Support for additional assistance.Feb 27, 15:02 PST Update - Our engineering team is continuing to monitor system performance. For customers located in Argentina impacted by this issue, please r
Started Mar 1, 2026 — Resolved Mar 1, 2026
Feb 28, 18:00 PST Completed - The scheduled maintenance has been completed.Feb 28, 14:00 PST In progress - Scheduled maintenance is currently in progress. We will provide updates as necessary.Feb 19, 07:47 PST Update - In order to increase the stability and scalability of our systems, we are performing scheduled maintenance on our infrastructure on February 28, from 2PM to 6PM PT. During this time, customers may experience failures when trying to create, update or delete lists, custom fields, se
Started Feb 26, 2026 — Resolved Feb 26, 2026
Feb 26, 11:23 PST Resolved - Our engineers have investigated and resolved an issue that caused high latency when sending email through SendGrid. From 8:24 AM PST to 9:15 AM PST on Thursday, February 26, 2026, customers may have experienced delays sending email from both the SendGrid dashboard (web app) and email sent via SMTP or API. The issue has been resolved, and all SendGrid email sending is operating normally across the dashboard, SMTP, and API.
Started Feb 12, 2026 — Resolved Feb 12, 2026
Feb 12, 10:36 PST Resolved - Our engineers have monitored the fix and confirmed the issue with Advanced Statistics has been resolved. All services are now operating normally at this time.Feb 12, 06:42 PST Update - Our engineering team has identified the root cause of the issue and is continuing to work on implementing a fix. We will provide the next update in four hours or as soon as additional information becomes available.Feb 12, 03:02 PST Update - Our engineering team has identified the root
Started Feb 11, 2026 — Resolved Feb 11, 2026
Feb 11, 12:33 PST Resolved - Our engineers have monitored the fix and confirmed the issue with Ticket Creation within the SendGrid Help Center has been resolved. All services are now operating normally at this time.Feb 11, 11:35 PST Update - We are continuing to monitor for any issues. We will provide another update in an hour or as soon as more information becomes available.Feb 11, 10:43 PST Update - We are continuing to monitor for any issues. We will provide another update in an hour or as so
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 33ms compared to 22ms for SendGrid.
Which is more reliable, Postmark or SendGrid?
From December 12th to March 12th, 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 December 12th to March 12th 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.