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 | 8th of 10 ↑ | 2 | 3 |
 | <1M | 10th of 10 → | 3 | 11 |
From January 1st to March 31st, Knock routed <1M messages through Mailersend and <1M through Sparkpost. Mailersend reported 3 status page updates over the last 90 days, while Sparkpost reported 11.
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 |
|---|---|---|---|---|
| 264ms | 548ms | 589ms | 802ms |
| 287ms | 346ms | 386ms | 542ms |
The chart above shows each provider's daily median response time (p50) from January 1st to March 31st. The top-line number is an average of these daily values: Mailersend averaged 264ms compared to 287ms for Sparkpost. Mailersend's highest daily p50 was 469ms; Sparkpost's was 336ms. Mailersend is 23ms 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 548ms compared to 346ms for Sparkpost. The highest daily p90 was 1048ms for Mailersend and 402ms for Sparkpost. Sparkpost handles these slower requests 202ms 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 802ms at p99 while Sparkpost reached 542ms. The highest daily p99 was 12094ms for Mailersend and 31566ms 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% |
|---|---|---|---|---|---|
| 0.01% | 0.06% | Feb 18 | 84 | 4 |
| 0.21% | 3.41% | Feb 24 | 89 | 1 |
Averaged across the date range, Mailersend shows a 0.01% daily error rate compared to 0.21% for Sparkpost. The highest single-day error rate was 0.06% for Mailersend and 3.41% for Sparkpost. Mailersend demonstrates a lower error rate, indicating slightly more consistent availability during this period. 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
Ongoing since Mar 30, 2026
Status: Scheduled Our database service provider will be performing scheduled maintenance that should take no longer than 15 minutes. During this time, you may experience brief interruptions when signing up, logging in, or switching accounts on MailerSend. We appreciate your patience and thank you for your continued trust in our services. Affected components MailerSend APP (Under maintenance)
Started Mar 3, 2026 — Resolved Mar 3, 2026
Status: Complete Maintenance has completed Affected components Bulk endpoint (Under maintenance) SMTP (Under maintenance) Delivery time (Under maintenance) Email sending API (Under maintenance) Deliverability rate (Under maintenance)
Started Feb 19, 2026 — Resolved Feb 19, 2026
Status: Resolved The issue has been resolved and systems have returned to normal. We’ll continue monitoring to ensure ongoing stability. Thank you for your patience. Affected components MailerSend APP (Operational)
Recent Sparkpost incidents
Recent status page incidents for Sparkpost
Started Mar 16, 2026 — Resolved Mar 16, 2026
Mar 16, 19:00 EDT Completed - The scheduled maintenance has been completed.Mar 16, 16:45 EDT Update - Scheduled maintenance is still in progress, the maintenance window has been extend by one hour to allow the maintenance to finish. During the full duration of this maintenance all emails will continued to be accepted. This maintenance only impacts our EU sending infrastructure.Mar 16, 15:00 EDT In progress - Scheduled maintenance is currently in progress. We will provide updates as necessary.
Started Mar 12, 2026 — Resolved Mar 12, 2026
Mar 12, 07:25 EDT Resolved - This incident has been resolved.Mar 12, 06:03 EDT Monitoring - System functionality has been fully restored and all emails are being transmitted correctly without added latencies; we are actively monitoring.Mar 12, 04:00 EDT Investigating - Email delivery in US is impacted, experiencing elevated delays.Mar 12, 03:48 EDT Monitoring - System is fully recovered and under monitoring.Mar 12, 02:51 EDT Investigating - We are currently investigating issues with delivery of
Started Mar 5, 2026 — Resolved Mar 5, 2026
Mar 4, 20:24 EST Resolved - This incident has been resolved.Mar 4, 20:00 EST Monitoring - We are observing recovery in email delivery performance and are actively monitoring.Mar 4, 19:51 EST Investigating - We are investigating an increase in delivery latency for some outbound messages.
Started Feb 27, 2026 — Resolved Feb 27, 2026
Feb 27, 12:38 EST Resolved - Microsoft has confirmed that they made additional changes the night of Thursday, Feb 26th that should have remediated most IP rate limiting and rejection issues. If you are still seeing impacts, please reach out via your normal support channels and our team can investigate and escalate with Microsoft.Feb 26, 12:55 EST Monitoring - We are currently seeing elevated temporary rejection rates for email delivered to Outlook.com, Hotmail, and other Microsoft-hosted addres
Started Feb 24, 2026 — Resolved Feb 24, 2026
Feb 24, 14:41 EST Resolved - This incident has been resolved.Feb 24, 14:38 EST Monitoring - A fix has been implemented and we are monitoring the results.Feb 24, 14:34 EST Identified - The team has identified the root cause. There is a core networking issue that has impacted sending across the clusters.Feb 24, 14:25 EST Update - We are continuing to investigate this issue. We still see 5xx errors on mail injections and degradation.Feb 24, 14:07 EST Update - We are continuing to investigate this
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
What is the difference between Mailersend and Sparkpost?
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.
Which is cheaper, Mailersend or Sparkpost?
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.
Which is faster, Mailersend or Sparkpost?
Based on real-world data from Knock, Mailersend has a median API response time (p50) of 264ms compared to 287ms for Sparkpost.
Which is more reliable, Mailersend or Sparkpost?
From January 1st to March 31st, Mailersend showed an error rate of 0.01% while Sparkpost showed 0.21%. 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, Mailersend or Sparkpost?
On the Knock platform, Mailersend handled <1M messages from January 1st to March 31st compared to <1M for Sparkpost. Mailersend is currently trending upward in adoption, while Sparkpost volume has remained stable.
Can I use both Mailersend and Sparkpost together?
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.
What are the main pros and cons of Mailersend vs Sparkpost?
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.