Uptime with measurement coverage
Availability for 24 hours, 7, 30 and 90 days. See which share of the period was actually observed.
Mail server monitoring
Detect server outages. Keep your email infrastructure in view.
Identify mail server disruptions, track availability and keep certificates and security policies in view. Sendequelle brings your monitoring results together in one place.
New sign-ins, trial accounts and orders are temporarily closed. The free checking tools are already available without an account.
Three layers of monitoring
Reachability
Does the mail server respond? Uptime and confirmed outages show its operational state.
Transport security
STARTTLS, certificates and DANE/TLSA show how connections are secured.
Policies and reports
DNS, SPF, DKIM, DMARC, MTA-STS and TLS-RPT provide further context.
Active scope depends on your plan entitlements and configured checks.
Continuous observation
From reachability to the cause
A single green status is not enough for operations. Check results, timestamps and incidents help you understand disruptions.
Certificates and STARTTLS
Track TLS connections, certificate validity and expiry dates. Security findings remain visible when the server is reachable.
DANE and MTA-STS
Check the binding of mail server certificates to TLSA and your MTA-STS policy within your enabled monitoring scope.
Outages and recovery
Confirmed disruptions and recoveries appear as incidents. Notifications use your activated channels.
Additional mail services
Explicitly activate enabled submission, IMAP or POP3 endpoints. Their reachability complements SMTP monitoring.
Reports and policies
DMARC and TLS-RPT analysis, DNS and authentication checks complement technical findings according to your plan.
Results you can interpret
Mail service responds
The technical response confirms reachability of the checked endpoint.
Security finding
An expired certificate or DANE mismatch is displayed as a separate finding.
No current measurement
Missing or stale results remain unknown. You can see the timestamp of the last check.
Uptime describes observed technical reachability. It does not prove successful delivery or availability of individual mailboxes.
In your account
How monitoring begins
1
Verify your domain
Add your domain and confirm ownership using the provided DNS record.
2
Configure monitoring
Review your plan scope, activate additional mail services and set up notifications.
3
Track operations
Open Monitoring for checks and history. Mail server uptime shows availability, measurement coverage and incidents.
Uptime included in platform plans
Choose domain limits and check intervals to suit your operations. These values come from the public new customer catalog.
Starter
3 domains
Check interval from 15 min
Business
15 domains
Check interval from 5 min
Pro
50 domains
Check interval from 1 min
MSP
150 domains
Check interval from 1 min
Free does not include continuous monitoring. Enterprise scope is agreed individually. The actual check schedule considers your assigned entitlements and activations; intervals are not a guaranteed notification time.
Monitoring questions
Detection depends on the check interval and confirmation of a disruption. Incidents open and close according to configured confirmation rules; enabled notification channels inform you.
SMTP on port 25 and explicitly activated additional services: submission with STARTTLS (587) or TLS (465), IMAP with STARTTLS (143) or TLS (993), and POP3 with STLS (110) or TLS (995). Checks use technical greetings and capabilities without authentication or mailbox access.
No sufficiently recent measurements are available for those periods. Sendequelle shows measurement coverage and marks gaps as unknown. History starts with your active monitoring.
Continuous HTTP uptime monitoring is not currently offered. This page describes the available mail server monitoring.
Keep your mail servers in view
Compare plans or start with a free public domain check.