Compare MailerSend against Resend API performance
Compare real-time performance, reliability, and uptime benchmarks for MailerSend and Resend, powered by proprietary data from billions of messages sent through Knock.
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 → | 0 | 2 |
 | 10M–25M | 1st of 10 → | 2 | 2 |
From August 13th to November 11th, Knock routed <1M messages through MailerSend and 10M–25M through Resend. MailerSend reported 2 status page updates over the last 90 days, while Resend reported 2.
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 |
|---|---|---|---|---|
| 269ms | 467ms | 696ms | 1635ms |
| 70ms | 102ms | 122ms | 304ms |
The chart above shows each provider's daily median response time (p50) from August 13th to November 11th. The top-line number is an average of these daily values: MailerSend averaged 269ms compared to 70ms for Resend. MailerSend's highest daily p50 was 730ms; Resend's was 96ms. Resend is 199ms 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 467ms compared to 102ms for Resend. The highest daily p90 was 3166ms for MailerSend and 146ms for Resend. Resend handles these slower requests 365ms 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 1635ms at p99 while Resend reached 304ms. The highest daily p99 was 43537ms for MailerSend and 1793ms for Resend, indicating the worst-case response time during spikes or provider-side congestion. Resend 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% | Aug 13 | 91 | 0 |
| 0.00% | 0.09% | Oct 1 | 89 | 2 |
Averaged across the date range, MailerSend shows a 0.00% daily error rate compared to 0.00% for Resend. The highest single-day error rate was 0.00% for MailerSend and 0.09% for Resend. 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 (Sun, 11 Oct 2026 07:10:00 GMT - Sun, 11 Oct 2026 07:40:00 GMT) Maintenance has completed Affected components Bulk endpoint (Operational) SMTP (Operational) Email activity (Operational) Delivery time (Operational) Email sending API (Operational) Email analytics (Operational) Deliverability rate (Operational) MailerSend APP (Operational)
Started Sep 21, 2026 — Resolved Sep 21, 2026
Status: Complete (Mon, 21 Sep 2026 07:00:00 GMT - Mon, 21 Sep 2026 07:05:00 GMT) Maintenance has completed Affected components Bulk endpoint (Operational) SMTP (Operational) Delivery time (Operational) Email sending API (Operational) Inbound routing (Operational)
Recent Resend incidents
Recent status page incidents for Resend
Started Oct 26, 2026 — Resolved Oct 26, 2026
Status: Resolved Email status updates are processing normally again. All delayed updates have been delivered, and no data was lost. Affected components Email Events (Operational)
Started Oct 23, 2026 — Resolved Oct 23, 2026
Status: Resolved We have resolved the underlying issue and service has been resumed. Affected components Single Email (Operational) Broadcast Emails (Operational) Batch Emails (Operational) Scheduled Emails (Operational)
Pros and cons
Compare the strengths and tradeoffs between MailerSend and Resend.
MailerSend
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
Cons
- Available integrations with other tools are basic and limited
- Fewer advanced features than enterprise platforms
- Smaller ecosystem compared to established competitors
Resend
Pros
- Beautiful documentation with attention to detail and great developer experience
- Created and maintain React Email, the go-to framework for building email templates in React
- Minimalist, developer-optimized platform that avoids bloat with a focused UI
- Transparent observability with real-time visibility into sends, failures, and engagement
Cons
- Newer and less battle-tested compared to incumbents like Mailgun or SendGrid
- Fewer enterprise features than established providers
- Limited marketing email capabilities
Pricing comparison
Compare MailerSend and Resend as your email volume grows.
Frequently asked questions
Mailersend is an intuitive transactional email and SMS service by Mailgun, designed for growing businesses. Resend is a modern email API built for developers, with React Email support and a focus on simplicity. MailerSend is best suited for growing saas + e-commerce, while Resend is geared toward developer-first, react teams.
Free tier includes 500 emails per month. Hobby is $7/month for 5,000 emails, with extra email at $1.50 per 1,000, and does not extend to 50,000 emails. Starter starts at $35/month for 50,000 emails and ends at 1 million. Professional starts at $110/month and published pricing ends at 2 million. Free tier includes 3,000 emails per month and 100 emails per day. Paid plans start at $20/month for 50,000 emails with overages at $0.90/1K on Pro, scaling down to $0.46/1K on Scale 2.5M. 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 269ms compared to 70ms for Resend.
From August 13th to November 11th, MailerSend showed an error rate of 0.00% while Resend 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 August 13th to November 11th compared to 10M–25M for Resend. MailerSend volume has remained stable, while Resend volume has remained stable.
Yes. Knock enables you to integrate multiple email providers into a single notification workflow. You can use MailerSend and Resend 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. Resend strengths include beautiful documentation with attention to detail and great developer experience and created and maintain react email, the go-to framework for building email templates in react. On the other hand, MailerSend drawbacks include available integrations with other tools are basic and limited, while Resend drawbacks include newer and less battle-tested compared to incumbents like mailgun or sendgrid.