MailerSend vs Sparkpost
Compare MailerSend and Sparkpost 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 | 7th of 10 ↓ | 1 | 2 |
| <1M | 10th of 10 ↓ | 2 | 6 |
From July 24th to October 22nd, Knock routed <1M messages through MailerSend and <1M through Sparkpost. MailerSend reported 2 status page updates over the last 90 days, while Sparkpost reported 6.
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.
| Provider | Median (p50) | p90 | p95 | p99 |
|---|---|---|---|---|
| 167ms | 349ms | 450ms | 1052ms |
| 324ms | 548ms | 571ms | 719ms |
The chart above shows each provider's daily median response time (p50) from July 24th to October 22nd. The top-line number is an average of these daily values: MailerSend averaged 167ms compared to 324ms for Sparkpost. MailerSend's highest daily p50 was 730ms; Sparkpost's was 528ms. MailerSend is 157ms 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, MailerSend has a p90 of 349ms compared to 548ms for Sparkpost. The highest daily p90 was 3166ms for MailerSend and 624ms for Sparkpost. MailerSend handles these slower requests 199ms 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, MailerSend reached 1052ms at p99 while Sparkpost reached 719ms. The highest daily p99 was 43537ms for MailerSend and 901ms for Sparkpost, indicating the worst-case response time during spikes or provider-side congestion. Sparkpost 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% | 0.00% | Jul 24 | 91 | 0 |
| 0.00% | 0.00% | Jul 24 | 91 | 0 |
Averaged across the date range, MailerSend shows a 0.00% daily error rate compared to 0.00% for Sparkpost. The highest single-day error rate was 0.00% for MailerSend and 0.00% for Sparkpost. 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 MailerSend incidents
Recent status page incidents for MailerSend
Started Oct 11, 2026 — Resolved Oct 11, 2026
Status: Complete Maintenance has completed Affected components Delivery time (Operational) Email sending API (Operational) Email analytics (Operational) Deliverability rate (Operational) MailerSend APP (Operational) Bulk endpoint (Operational) SMTP (Operational) Email activity (Operational)
Started Sep 21, 2026 — Resolved Sep 21, 2026
Status: Complete Maintenance has completed Affected components Inbound routing (Operational) Bulk endpoint (Operational) SMTP (Operational) Delivery time (Operational) Email sending API (Operational)
Recent Sparkpost incidents
Recent status page incidents for Sparkpost
Started Oct 11, 2026 — Resolved Oct 11, 2026
Oct 11, 16:57 EDT Resolved - This incident has been resolved. Oct 11, 14:17 EDT Monitoring - A fix has been implemented and we are monitoring the results. Oct 11, 14:17 EDT Update - We are continuing to work on a fix for this issue. Oct 11, 14:09 EDT Update - We are continuing to rollout the new root signing keys from ICANN. We continue to see recovery across our global clusters. Oct 11, 13:51 EDT Identified - We are investigating an increase in delayed (deferred) messages in both
Started Oct 1, 2026 — Resolved Oct 1, 2026
Oct 1, 13:36 EDT Resolved - This issue has been resolved. Since our changes went in, we've seen no further delivery delays, including through peak sending periods. Email is being delivered normally. We apologize for the disruption and thank you for your patience. Oct 1, 13:16 EDT Monitoring - We've made changes to address the intermittent delivery delays. Since then, email has been delivered without delay, including during peak sending periods that previously caused the slowdowns. We're wa
Started Sep 17, 2026 — Resolved Sep 17, 2026
Sep 17, 06:00 EDT Resolved - This incident has been resolved. Sep 17, 05:47 EDT Monitoring - A fix has been implemented and we are monitoring the results. Sep 17, 05:06 EDT Investigating - We are investigating an increase in delivery latency for some outbound messages. (NOTE: This does not impact our customers hosted in the EU.)
Started Sep 14, 2026 — Resolved Sep 14, 2026
Sep 14, 12:46 EDT Resolved - The data has all been posted. We apologize for the delay. Sep 14, 12:31 EDT Monitoring - Data is reprocessed and loads are completing. Full data recovery expected in the next 30 minutes. Sep 14, 10:59 EDT Identified - We know what has caused the data delay and are working to get the data posted. Sep 14, 10:19 EDT Investigating - Health score and Cohort data is delayed.
Started Aug 27, 2026 — Resolved Aug 27, 2026
Aug 27, 18:56 EDT Resolved - The Apple bounce levels have maintained at pre incident levels during our monitoring phase. Our clean up of the bad suppressions has finished. This incident is resolved. Aug 27, 15:28 EDT Monitoring - We have seen recovery of the Apple private relay domain to pre-event bounce levels. Our team is actively working on automatically removing any suppressions that were created by this event. We anticipate the cleanup to be completed by 6PM EDT. Aug 27, 15:10 EDT
Pros and cons
MailerSend
Sparkpost
Pros
- Designed for both developers and business users with API and visual editor
- Modern, intuitive UI that is easier to navigate than older platforms
- Multi-channel support with native email and SMS transactional messaging
- Affordable Hobby plan at $7/month for 5,000 emails with low overage rates
Pros
- Delivers nearly 40% of all commercial email worldwide
- Subaccount support for isolated sending streams under one billing account
- On-premise mail sending solution available for very high volume workloads
- Great analytics tools with predictive health scores for email deliverability
Cons
- Available integrations with other tools are basic and limited
- Fewer advanced features than enterprise platforms
- Smaller ecosystem compared to established competitors
Cons
- Documentation can be hard to navigate with less beginner-friendly getting started content
- Higher price point than basic providers
- Now part of Bird (formerly MessageBird), which may affect product direction
Frequently asked questions
Mailersend is an intuitive transactional email and SMS service by Mailgun, designed for growing businesses. SparkPost is a data-driven email delivery platform with advanced analytics and predictive tools for high-volume senders. MailerSend is best suited for growing saas + e-commerce, while Sparkpost is geared toward data-driven, high-volume.
Free tier includes 500 emails per month. Paid plans start at $7/month for 5,000 emails on the Hobby plan, with the Starter plan at $35/month for 50,000 emails. Free tier includes 500 emails per month with community support. Paid plans start at $20/month for 50,000 emails with premium deliverability features. The best value depends on your sending volume. Use the pricing calculator above to compare costs at your expected volume.
Based on real-world data from Knock, MailerSend has a median API response time (p50) of 167ms compared to 324ms for Sparkpost.
From July 24th to October 22nd, MailerSend showed an error rate of 0.00% while Sparkpost 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.
On the Knock platform, MailerSend handled <1M messages from July 24th to October 22nd compared to <1M for Sparkpost. MailerSend is currently seeing declining volume, while Sparkpost is seeing declining volume.
Yes. Knock enables you to integrate multiple email providers into a single notification workflow. You can use MailerSend and Sparkpost side by side, route traffic between them, or migrate from one to the other without changing your application code.
MailerSend strengths include designed for both developers and business users with api and visual editor and modern, intuitive ui that is easier to navigate than older platforms. Sparkpost strengths include delivers nearly 40% of all commercial email worldwide and subaccount support for isolated sending streams under one billing account. On the other hand, MailerSend drawbacks include available integrations with other tools are basic and limited, while Sparkpost drawbacks include documentation can be hard to navigate with less beginner-friendly getting started content.
Use either provider with Knock
Knock enables you to integrate MailerSend, Sparkpost, or any combination of email providers into a single notification workflow. Manage templates, orchestrate cross-channel delivery, and switch providers without changing your code.