TRUSTED SINCE 2018 • MILLIONS OF TESTS PER MONTH • 10,000+ BUSINESSES WORLDWIDE

Round-trip SMTP Email Monitoring 100% Free Forever

Small email delays can be costly for your business. MailFlowMonitoring provides round-trip SMTP monitoring, continuously testing your email infrastructure by sending test emails and tracking responses. Detect deliverability issues, server outages, and routing problems before they impact your users and customers.

Real-time Monitoring Second-by-second updates
99.9% Uptime Enterprise reliability
Instant Alerts Multi-channel notifications
Start Monitoring Free View Features

No credit card required • Setup in 5 minutes • Free forever

How Round-trip SMTP Monitoring Works

Continuous testing ensures your email infrastructure is always operational

1

We Send Test Emails

Our monitoring endpoints continuously send test emails to addresses you specify in your domain, simulating real email traffic.

2

Your Server Auto-Responds

Configure your SMTP server to automatically respond to our test emails. We track response times and delivery success.

3

Instant Alerts on Issues

If responses fail or exceed your configured thresholds, we immediately alert you via email, SMS, webhook, or PagerDuty.

What Round-trip Monitoring Validates

  • MX records are correctly configured for your SMTP servers
  • SMTP servers and relay software are up and running
  • Internet connection is active (for self-hosted or co-located servers)
  • Spam filters are not delaying or blocking legitimate email delivery
  • Complete email routing path is functioning correctly

Complete Email Infrastructure Monitoring

Round-trip SMTP monitoring with performance metrics and header analysis

Round-trip SMTP Tests

Continuous inbound and outbound email tests with complete header analysis and transaction logging.

Multi-channel Alerts

Configurable real-time alerts via email, SMS, webhook, PagerDuty, and Slack when thresholds are exceeded.

Performance Metrics

Track response times, delivery success rates, and historical statistics to optimize mail server performance.

Customizable Timeouts

Configure monitoring intervals and timeout thresholds based on your specific business requirements.

Transaction Logging

Complete log of all test emails sent and received, helping diagnose routing and blacklisting issues.

24/7 Monitoring

Day and night continuous testing ensures you're alerted to disruptions the moment they happen.

Why We Offer This Service for Free

As an email service provider, we needed to track mail flow problems through a large number of inbound email servers. Unlike services that deliver to a single MX record, we needed to specify individual IP addresses for message delivery.

We found existing services, but at $500+ per month, the cost exceeded our budget. So we built our own solution. Since launching in 2018, it worked so well that we decided to democratize mail flow monitoring by offering it free to everyone.

Today, we run millions of monitoring tests per month for over 10,000 businesses worldwide. Other free tools limit you to one server per account - impractical for organizations with substantial infrastructure. We built the tool we wanted to use, with the alerting integrations we needed, and we hope you find it valuable for your needs.

Our Philosophy: Essential infrastructure monitoring should be accessible to everyone, regardless of budget. Since 2018, we've been proving that enterprise-grade monitoring can be both powerful and free.

You're in Complete Control

Unlimited Monitoring

Monitor unlimited email servers and create unlimited notification policies without any restrictions.

Custom Intervals

Control how often we check your servers, from every minute to hourly intervals.

Flexible Thresholds

Set Round Trip Time thresholds and Notification Delay Rates that match your requirements.

Multi-channel Alerts

Email, SMS, webhook, PagerDuty, Slack - configure alerts through any channel for each monitoring policy.

Start Monitoring Your Email Infrastructure

Join thousands of businesses ensuring their email reliability. Setup takes less than 10 minutes.

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No credit card required • Free forever • Cancel anytime