SMTP Monitoring for Outbound & Inbound Mail Servers
Continuously connect to your mail servers from locations around the world, complete the full SMTP handshake, and verify STARTTLS and certificate health on every check. Catch handshake failures, expiring certificates, and slow responses before your customers tell you they never got your emails.
Comprehensive SMTP Monitoring Features
Everything you need to keep mail flowing reliably
Full SMTP Handshake
We open a real connection and run the HELO/EHLO exchange, confirming your server accepts mail rather than just answering a TCP port.
STARTTLS Verification
Check that your server advertises and successfully negotiates STARTTLS, so messages are encrypted in transit the way you expect.
TLS Certificate Expiry
Track the validity and expiry date of your mail server's TLS certificate and get warned well before it lapses and breaks delivery.
Response Time Tracking
Measure how quickly your server completes the handshake on every check so you can catch a slow, overloaded mail server early.
Smart Alerting
Get notified within seconds when the handshake fails, STARTTLS breaks, or latency crosses your threshold, via email, Slack, Discord, and webhooks.
Multi-Location Confirmation
Failures are confirmed from several regions before an incident opens, so a single bad network path never pages you with a false alarm.
Any SMTP Port
Monitor mail on standard SMTP ports including 25, 587, and 465, whether you run relay, submission, or implicit-TLS endpoints.
Historical Trends
Review availability and response time over time with clear graphs and reports, perfect for spotting slow regressions and proving uptime.
Why Choose Our SMTP Monitoring Solution?
When email silently stops flowing, you usually find out from an angry customer rather than a dashboard. Our SMTP monitoring connects to your mail servers like a real client, runs the full handshake, and checks STARTTLS and certificate health on every probe. With global probe locations, multi-region confirmation, and certificate-expiry warnings, you get an early-warning system for both outbound and inbound mail around the clock.
Verify outbound and inbound mail servers accept connections
Full HELO/EHLO handshake, not just a port check
STARTTLS negotiation and encryption verification
TLS certificate validity and expiry warnings
Multi-location checks to rule out local network issues
Response-time tracking and configurable thresholds
Historical availability and latency reports
Instant notifications via email, Slack, Discord, and more
How SMTP Monitoring Works
Simple setup, complete mail-server visibility
Add Your Mail Server
Enter your mail server's hostname and port, and choose the regions you want to connect from.
Set Your Checks
Decide whether to require STARTTLS, set acceptable response-time limits, and how many regions must agree before an alert fires.
Monitor 24/7
Our global network connects to your server continuously, completing the handshake and inspecting STARTTLS and certificate health from every location.
Get Instant Alerts
When the handshake fails, a certificate is about to expire, or response time degrades, you get immediate notifications and a detailed incident timeline.
SMTP Monitoring Use Cases
Perfect for any mail server that has to keep delivering
Transactional Email Servers
Password resets, receipts, and confirmations all depend on your SMTP server accepting mail. Know the instant it stops responding, long before customers report missing emails.
Certificate Expiry Protection
An expired TLS certificate can quietly break STARTTLS and stop delivery to strict recipients. Get warned days in advance so you can renew before mail flow is ever affected.
Inbound Mail Gateways
Your MX and relay servers must keep accepting connections to receive customer email. Monitor them from the outside to confirm inbound mail is never silently rejected or dropped.
Self-Hosted Mail Infrastructure
Running your own Postfix, Exim, or Microsoft Exchange stack means you own its uptime. Continuous SMTP checks catch handshake, TLS, and latency problems before they spread.
Frequently Asked Questions
Everything you need to know about SMTP monitoring
From our blog
Guides, deep-dives, and best practices from the WatchFor team
Ready to Start Monitoring Your Mail Servers with SMTP Checks?
Join the teams who trust our platform to keep watch over their outbound and inbound mail servers. Get started in minutes with our free plan — no credit card required.