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 | 11 |
| 500M+ | 2nd of 10 → | 9 | 25 |
From February 11th to May 12th, 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 February 11th to May 12th. The top-line number is an average of these daily values: Postmark averaged 24ms compared to 22ms for SendGrid. Postmark's highest daily p50 was 57ms; SendGrid's was 24ms. 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 87ms compared to 76ms for SendGrid. The highest daily p90 was 143ms 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 231ms at p99 while SendGrid reached 416ms. The highest daily p99 was 38235ms for Postmark and 5462ms 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% |
|---|---|---|---|---|---|
| 0.03% | 2.37% | Mar 27 | 86 | 2 |
| 0.00% | 0.03% | Feb 11 | 85 | 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 0.03% 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 Apr 21, 2026 — Resolved Apr 21, 2026
Good news - this issue has been resolved and everything should be working normally now. We're continuing to monitor closely to make sure everything stays stable. Thank you so much for your patience while we worked through this.
Started Apr 8, 2026 — Resolved Apr 9, 2026
**[UPDATE]** We determined that yesterday's network instability was caused by a widespread Google (Gmail) outage. You can find more information on Google’s Status Dashboard here: https://www.google.com/appsstatus/dashboard/incidents/224ozRqzW4sFBDK8hLnT We will share an additional update regarding our internal action items later today.
Started Apr 2, 2026 — Resolved Apr 3, 2026
**[UPDATE]** On **April 2nd** starting at **~07:00pm UTC**, Postmark experienced an incident that resulted in delayed message delivery and webhook notifications for some customers. The issue was caused by an infrastructure configuration change that disrupted internal mail routing. While messages were safely queued in a "Processing" state, they were not delivered until the routing configuration was restored. Service was restored on **April 3rd at ~4:20am UTC** and the backlog of queued message
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.
Recent SendGrid incidents
Recent status page incidents for SendGrid
Started May 8, 2026 — Resolved May 8, 2026
May 8, 01:09 PDT Resolved - Our engineers have monitored the fix and confirmed the issue with Mail delay has been resolved. All services are now operating normally at this timeMay 8, 00:04 PDT Update - Our engineering team has identified the root cause of the issue and is actively working on a resolution. Please note that new Mail Send requests are processing as expected and are not impacted. We will share another update within the next two hours, or sooner if additional information becomes av
Started May 6, 2026 — Resolved May 6, 2026
May 6, 16:22 PDT Resolved - Our engineers have monitored the fix and confirmed the issue with Twilio SendGrid invoices and the tax amounts has been resolved. All services are now operating normally at this time.May 6, 15:04 PDT Monitoring - Our engineers have implemented a fix and are monitoring system performance. We have resolved the tax calculation issue, and customer invoices have been corrected with the appropriate tax amounts. If you were overcharged, your refund will be automatically pr
Started May 5, 2026 — Resolved May 5, 2026
May 5, 09:17 PDT Resolved - Our engineers have successfully completed processing all delayed Engagement Tracking and Segmentation data for Legacy Marketing Campaigns. All contact engagement data and segmentation features are now fully up-to-date and functioning normally. We sincerely apologize for any inconvenience this delay caused. This issue is now resolved, but if you experience any further issues please reach out to our SendGrid Technical Support Team for further assistance.May 4, 09:43 P
Started Apr 23, 2026 — Resolved Apr 23, 2026
Apr 23, 14:18 PDT Resolved - Our engineers have monitored the fix and confirmed the issue with module movement in the Design Editor has been resolved. All services are now operating normally at this time.Apr 23, 10:16 PDT Update - Our team is still investigating this issue, and we still don't have updates to provide. For now, latest recommendation persist: For the best experience, please use the latest version of Safari or Firefox while we work on a fix. We will provide another update as soon
Started Apr 18, 2026 — Resolved Apr 18, 2026
Apr 18, 13:07 PDT Resolved - Our engineers have investigated and resolved the issues with delayed delivery of emails for a subset of customers. From 12:05 pm PST to 12:45 pm PST customers may have seen a delay in the delivery of their emails. The issue has been resolved and 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 24ms compared to 22ms for SendGrid.
Which is more reliable, Postmark or SendGrid?
From February 11th to May 12th, 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 February 11th to May 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.