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) |
|---|---|---|---|---|
| 1M–10M | 4th of 10 ↓ | 4 | 12 |
| 100M–500M | 2nd of 10 → | 25 | 25 |
From July 4th to October 2nd, Knock routed 1M–10M messages through Postmark and 100M–500M through SendGrid. Postmark reported 12 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 July 4th to October 2nd. The top-line number is an average of these daily values: Postmark averaged 62ms compared to 15ms for SendGrid. Postmark's highest daily p50 was 209ms; SendGrid's was 21ms. SendGrid is 47ms 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 209ms compared to 34ms for SendGrid. The highest daily p90 was 250ms for Postmark and 66ms for SendGrid. SendGrid handles these slower requests 175ms 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 408ms at p99 while SendGrid reached 107ms. The highest daily p99 was 1224ms for Postmark and 148ms 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% | 0.01% | Aug 30 | 89 | 0 |
| 0.00% | 0.00% | Jul 4 | 91 | 0 |
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 0.01% for Postmark and 0.00% 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 Sep 28, 2026 — Resolved Sep 28, 2026
This has been resolved. All inbound webhooks processing have been caught up. No messages have been lost.
Started Sep 28, 2026 — Resolved Sep 28, 2026
This incident has been resolved. The backlog of messages queued during the delay between 9:49 AM and 10:07 AM CT (10:49–11:07 AM ET) has been fully processed and delivered. New messages continue to be accepted and delivered normally. No messages were lost. If you have questions about a specific message, please reach out to us at [email protected].
Started Sep 22, 2026 — Resolved Sep 22, 2026
A subset of messages accepted between 2:15 pm and 2:35 pm EDT on September 22 (18:15 – 18:35 UTC) were held in queue due to a processing issue instead of being delivered immediately. Those messages were fully processed and delivered at 3:38 pm EDT on September 24 (19:38 UTC). No messages were lost. Messages accepted outside of this 20-minute window were not affected and were delivered normally. If you have questions about a specific message, please reach out to us at [email protected]
Started Sep 17, 2026 — Resolved Sep 17, 2026
Some users were experiencing problems with our service from 4:15 pm to 5:25 pm EDT, resulting in a page titled "Something went wrong". We have identified the root of the issue and have applied a remediating solution. If you are still encountering this page after clearing your site data, cache & cookies, please reach out to us at [email protected].
Started Aug 24, 2026 — Resolved Aug 24, 2026
We've now resolved the incident. Stats data has caught up and is now displaying in real time. This issue occurred from approximately 13:45 EDT to 16:25 EDT on August 24, 2026. Thank you for your patience.
Recent SendGrid incidents
Recent status page incidents for SendGrid
Ongoing since Nov 19, 2026
THIS IS A SCHEDULED EVENT Nov 18, 21:00 PST - Nov 19, 03:00 PST Sep 30, 16:04 PDT Scheduled - Our SMS carrier partner in the United States is conducting a planned maintenance from 18 November 2026 at 21:00 PST until 19 November 2026 at 03:00 PST. During the maintenance window, there could be intermittent delays delivering SMS to and from United States handsets via subset of United States long codes.
Ongoing since Nov 17, 2026
THIS IS A SCHEDULED EVENT Nov 16, 21:00 PST - Nov 17, 03:00 PST Sep 30, 13:34 PDT Scheduled - Our SMS carrier partner in the United States is conducting a planned maintenance from 16 November 2026 at 21:00 PST until 17 November 2026 at 03:00 PST. During the maintenance window, there could be intermittent delays delivering SMS to and from United States handsets via subset of United States long codes.
Ongoing since Oct 29, 2026
THIS IS A SCHEDULED EVENT Oct 28, 20:00 PDT - Oct 29, 00:00 PDT Sep 29, 08:15 PDT Scheduled - Our SMS and MMS carrier partner in the United States is conducting a planned maintenance from 28 October 2026 at 20:00 PDT until 29 October 2026 at 00:00 PDT. During the maintenance window, there could be intermittent delays delivering SMS and MMS to United States handsets via subset of United States long codes.
Ongoing since Oct 29, 2026
THIS IS A SCHEDULED EVENT Oct 28, 20:00 PDT - Oct 29, 00:00 PDT Sep 4, 00:24 PDT Scheduled - Twilio is conducting a planned maintenance from 28 October 2026 at 20:00 PDT until 29 October 2026 at 00:00 PDT. During the maintenance window, there could be intermittent delays or failures delivering SMS and MMS to and from United States and Canada handsets when sending via long codes, short codes and toll free numbers.
Ongoing since Oct 28, 2026
THIS IS A SCHEDULED EVENT Oct 28, 13:00 - 17:00 PDT Oct 2, 07:46 PDT Scheduled - The Tele2 network in Russia is conducting a planned maintenance from 28 October 2026 at 13:00 PDT until 28 October 2026 at 17:00 PDT. During the maintenance window, there could be intermittent delays delivering SMS to Tele2 Russia handsets.
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 62ms compared to 15ms for SendGrid.
Which is more reliable, Postmark or SendGrid?
From July 4th to October 2nd, 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 1M–10M messages from July 4th to October 2nd compared to 100M–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.