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 → | 13 | 25 |
From January 1st to April 1st, 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 January 1st to April 1st. The top-line number is an average of these daily values: Postmark averaged 32ms compared to 22ms for SendGrid. Postmark's highest daily p50 was 57ms; SendGrid's was 28ms. 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 93ms compared to 76ms for SendGrid. The highest daily p90 was 143ms for Postmark and 98ms for SendGrid. SendGrid handles these slower requests 17ms 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 242ms at p99 while SendGrid reached 268ms. The highest daily p99 was 38235ms for Postmark and 1255ms for SendGrid, indicating the worst-case response time during spikes or provider-side congestion. Both providers exhibit comparable tail response times, meaning neither is significantly more prone to outlier slowdowns.
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% |
|---|---|---|---|---|---|
| 0.03% | 2.37% | Mar 27 | 83 | 4 |
| 0.00% | 0.02% | Jan 21 | 81 | 4 |
Averaged across the date range, Postmark shows a 0.03% daily error rate compared to 0.00% for SendGrid. The highest single-day error rate was 2.37% 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 Mar 27, 2026 — Resolved Mar 28, 2026
We've resolved the incident. Thanks for your patience.
Started Mar 26, 2026 — Resolved Mar 26, 2026
The issue has been resolved.
Started Mar 25, 2026 — Resolved Mar 25, 2026
The issue has been resolved! Thank you for patience.
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.
Recent SendGrid incidents
Recent status page incidents for SendGrid
Ongoing since Apr 11, 2026
THIS IS A SCHEDULED EVENT Apr 11, 04:00 - 08:00 PDTMar 31, 12:23 PDT Scheduled - In order to increase the stability and scalability of our systems, we are performing scheduled maintenance on our Production database on Saturday, April 11, from 4PM-8PM PDT. During this time, incoming category statistics will be delayed in being written to the database, and metrics may lag as a result. Requests for category statistics may also be temporarily unavailable while we perform the maintenance. Thank you
Started Mar 25, 2026 — Resolved Mar 25, 2026
Mar 25, 13:58 PDT Resolved - From 9:08 AM PT - 9:22AM PT today, customers in the EU region may have experienced mail delay for up to 14 minutes. Customer may have received "Internal Deferral" errors when attempting to send mail at this time. Our engineers have investigated and resolved the issue. All impacted services are operating normally.
Started Mar 19, 2026 — Resolved Mar 19, 2026
Mar 18, 19:17 PDT Resolved - Our engineers have monitored the fix and confirmed the issue with CAPTCHA has been resolved. All services are now operating normally at this time.Mar 18, 14:54 PDT Monitoring - Our engineers have implemented a fix and are monitoring system performance. Users that were previously impacted by failed CAPTCHA errors should now have the capacity to login without issue. We will provide another update in an hour or as soon as more information becomes available.Mar 18, 14:32
Started Mar 19, 2026 — Resolved Mar 19, 2026
Mar 18, 19:00 PDT Completed - The scheduled maintenance has been completed.Mar 18, 17:00 PDT In progress - Scheduled maintenance is currently in progress. We will provide updates as necessary.Mar 15, 09:57 PDT Scheduled - To ensure our support tools stay fast and reliable, we’ll be performing some scheduled maintenance on Wednesday, March 18th, from 5:00 PM to 7:00 PM PDT. During this two-hour window, our Live Chat and Personalized Support phone lines will be temporarily unavailable. Here’s how
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
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 32ms compared to 22ms for SendGrid.
Which is more reliable, Postmark or SendGrid?
From January 1st to April 1st, Postmark showed an error rate of 0.03% 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 January 1st to April 1st 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.