MailflowMon
Round-trip mail observability

Watch every message travel your mail path — in real time.

MailflowMon sends a real probe through your production SMTP every five minutes, follows it through forwarding, parses SPF/DKIM/DMARC, and pages you the instant the round trip slows or breaks.

Start monitoring — free See live demo
No credit card Open REST API
Live probe stream last 60s · 5 probes
monitor-1.example
queued → relay → inbox
7.4 s spf · dkim · dmarc
support.example
queued → relay → inbox
9.1 s spf · dkim · dmarc
marketing.example
queued → relay → inbox
23.8 s slow
noreply.example
queued → relay → inbox
6.2 s spf · dkim · dmarc
alerts.example
queued → relay → inbox
8.0 s spf · dkim · dmarc
P50 8.2 s · P95 16.4 s Uptime 30d 99.86%

Why blackbox checks miss it

Port 25 is up. Mail is down. Both can be true.

Traditional uptime monitors stop at the TCP handshake. Real email outages live further down the path — in queues, in DKIM mismatches, in spam filters quietly dropping legitimate sends.

  • Ping-style monitors can't see deliveryA 200 OK from your MX doesn't mean a real message arrived in 12 seconds.
  • Auth drift is invisibleSPF passing today, DKIM silently failing tomorrow. You find out from a support ticket.
  • Slow ≠ down — but feels worseA 4-minute round trip is a P1 for transactional mail, even if every check is technically green.

One probe · one round trip

SMTP submit
your outbound relay
0.31 s
Your MX
queued → relayed
1.84 s
SPF · DKIM · DMARC
Authentication-Results parsed
pass
IMAP read
monitor mailbox
7.4 s

What you get

Everything you need to keep mail flowing

Six things MailflowMon does that ping-style monitors don't.

End-to-end email testing

Sends real test emails through your mail servers and verifies delivery. Measures round-trip time from send to receive.

SPF, DKIM & DMARC checks

Every test email is analyzed for authentication headers. Know immediately when your email authentication is misconfigured.

Instant alerts

Get notified via email or webhook the moment a monitor goes DOWN — and again when it's back UP. Configurable failure thresholds.

Historical statistics

Track delivery success rates, response times, and authentication results with hourly, daily, and weekly aggregated statistics.

REST API

Integrate monitoring data into your own tools using the REST API. Retrieve monitors, results, and statistics programmatically.

Multi-domain support

Monitor multiple domains and email servers from a single account. Each domain is verified via DNS TXT records.

See it in product

Everything in one console

Dashboards, per-monitor detail pages, and public status pages — all generated from the same probe results. Open the full live demo →

mailflowmon/dashboard
Domains
3 / 3
all verified
Monitors
5 / 5 active
1 degraded
Uptime · 24h
99.86%
across all monitors
Avg RTT · 24h
460ms
last 24 hours
Inbound MX
[email protected]
220ms
100%Uptime 24h
Support inbox
[email protected]
1.4s
99.31%Uptime 24h
Marketing relay
[email protected]
310ms
99.94%Uptime 24h
mailflowmon/monitors/3
degraded public · /status/<token>

Support inbox

[email protected] · every 5 min · 60s timeout

Uptime · 24h
99.31%
286 of 288 succeeded
Uptime · 7d
99.86%
2013 of 2016 succeeded
Avg RTT · 7d
980ms
p95 2.2s · max 4.8s
Auth pass · 7d
100%
SPF · DKIM · DMARC

Uptime · 30 days

mailflowmon/status/<token>

All systems operational

Outbound mail is flowing within expected latency. No active incidents.

Last test 14s ago

Uptime — last 90 days

99.86% 12,442 of 12,460 checks succeeded over 90 days
mailflowmon/alerts

Configured alerts

[email protected]
down ≥ 3 slow > 5s
Enabled
https://hooks.demo.example/mailflow
down ≥ 3
Unverified
Enabled

How we compare

Mail monitoring that actually checks mail

Most "uptime" tools stop at the protocol layer. MailflowMon measures the whole path your customers see.

Capability Generic uptime monitor Blackbox SMTP probe MailflowMon
Confirms port 25 / 587 is reachable Yes Yes Yes
Sends a real, tagged message end-to-end No Partial Yes
Measures full round-trip time No No Yes
Parses SPF / DKIM / DMARC results No No Yes
State-machine alerts (no spam on flapping) Limited No Yes
Public status pages + embed badges Paid No Free
Open REST API No Sometimes Yes

Built for engineers

Pull any probe, any chart, into your stack.

Bearer-token REST API. JSON in, JSON out. Drop results straight into Grafana, your incident runbook, or your weekly reliability report.

  • Per-monitor, per-domain, or per-result queries
  • Tiered aggregation: raw, hourly, daily, weekly
  • Webhook delivery for any alert state change
  • 60 req/min default rate limit, raise on request
curl · GET /v1/monitors/42/results 
# Last 24h of probes for monitor 42
curl -H "Authorization: Bearer mf_live_…" \
     "https://mailflowmon.com/v1/monitors/42/results?range=24h"

{
  "monitor_id": 42,
  "domain": "monitor-1.example",
  "uptime_30d": 0.9986,
  "results": [
    {
      "sent_at":  "2026-05-20T14:18:02Z",
      "rtt_seconds": 7.42,
      "spf":  "pass",
      "dkim": "pass",
      "dmarc": "pass",
      "state": "up"
    }
  ]
}

Plays well with your stack

Push alerts where your team already lives. Pull data where you already chart it.

Slack
Discord
Grafana
Datadog
PagerDuty
Webhooks

Get your first probe in five minutes.

Add a TXT record, point one alias at our IMAP inbox, and the dashboard fills up while you finish your coffee.

Create your free account
Free forever — no card required 3 domains · 5 monitors · 90 days history