No account required
Check blocklists
Check MX and explicitly discovered SPF sender IP addresses using an approved reputation provider.
Open check
Clarity for your email infrastructure
Understand your email infrastructure. Monitor and protect it.
Check your domain’s public DNS and email security settings. Sendequelle helps you understand findings and, when needed, track changes and incidents over time.
- No account required
- Complete basic result
- No email address required
Free domain trust check
What can others see?
Check your domain’s MX, SPF, DKIM, DMARC and transport protection. Website and reputation findings are additional information and do not affect the email score.
DANE has high priority: missing protection deducts 8 points and caps the rating at BBB. Without a usable DANE policy, missing, disabled or testing-only MTA-STS deducts another 3 points. With a DANE policy published at every MX, MTA-STS is recommended without a deduction.
We check public DNS records and safely accessible HTTPS information. Mailboxes are never accessed.
Completed public checks may appear in the weekly overview with the domain, rating and time. Verified owners can hide their domain at any time.
Free tools
Investigate a specific issue
Choose a focused check or assess your whole domain. Each result explains the finding, its meaning and the next step.
No account required
Check DMARC
Check the effective DMARC policy, SPF/DKIM alignment settings and reporting destinations.
Open check
No account required
Check SPF
Check SPF syntax, mechanisms, dependencies, DNS lookup limits and network ranges.
Open check
No account required
Check MX and DNS
Check mail routing, target resolution, null MX, DNSSEC and redundancy indicators.
Open check
No account required
Check MTA-STS
Check the TXT record, safely retrieved HTTPS policy and MX coverage.
Open check
No account required
Check TLS-RPT
Check the TLS-RPT record, reporting URI syntax and DNS evidence.
Open check
Inside the product
Your email operations at a glance
The dashboard brings domain status, open incidents and reports together. Filters focus the view; saved views take you back to recurring tasks.
Prioritise domains
Status, coverage and the last check show where to take a closer look.
Understand incidents
Move from a finding to its timeline and technical evidence, with a clear next step.
Review abuse reports
Filter reports by folder, period and status, then review them manually with your team.
Check Gmail, Outlook & Yahoo requirements
Does your sending domain meet Gmail, Outlook.com and Yahoo’s technical requirements? Check published DNS prerequisites and see which evidence is still needed for actual sending.
Public DNS and limited HTTPS checks run in the background; no SMTP, mailbox or tenant access. A shared five-minute domain cooldown also applies to the domain check.
Completed public checks may temporarily appear in the weekly overview with domain, Domain Trust rating and time. Verified owners can opt out. Private account findings remain private.
Check Gmail, Outlook & Yahoo requirements · Your recipients’ requirements
From an administrator, for administrators
Built because I needed this tool myself.
I am Norbert Sehm. I run my own email services and understand the responsibility of maintaining infrastructure that people rely on every day.
I deliberately use DANE when running my email services. Certificate renewal was automated; checking it against the TLSA records was not yet. That led me to automate my technical checks on Linux – and eventually to build Sendequelle.
Secure email is part of my daily work. Sendequelle is my tool for it.
Email Security Hall of Fame · 2025
Gold status for emailn.de, firemail.de and skymail.de.
Module in your Sendequelle account
Explore the account module
Email forensics in your account
Understand headers and message files, trace delivery routes and compare private messages with your own references. Available after signing in to your Sendequelle account.
Transparent assessment
Real results from this week
The ranking shows eligible public checks from this week using stored results with sufficient coverage. Viewing this page does not start a scan. Verified owners can hide their domain at any time.
Top 5 this week
11/02/2026 to 11/08/2026 · at least 75% coverage and six assessable email signals
Leading ratings
Current results from 90 points with a leading A rating and evidenced DANE policy.
firemail.deChecked 04.11.2026 12:44
AAA · 98/100Findings & next steps
skymail.deChecked 03.11.2026 07:14
AAA · 98/100Findings & next steps
1–2 of 2 results Page 1 of 1
Room for improvement
Current results below 90 points or subject to a rating cap, with findings and next steps.
No sufficiently supported public results in this group yet.
0 results Page 1 of 1
Ratings are technical snapshots, not certifications or guarantees. Ties are resolved by coverage, freshness and domain name.
Monthly domain security report
Individual checks reveal trends over time
Sendequelle publishes only sufficiently large anonymised monthly aggregates, with sample sizes, confidence intervals and sampling limitations, without a permanent list of individual domains.
Continuous monitoring
A check is a snapshot. Sendequelle detects changes.
Mail server uptime in view
Reachability, confirmed outages and recoveries with uptime history and visible measurement coverage.
Monitor infrastructure
Scheduled checks monitor DNS, MX, SMTP STARTTLS, DANE, MTA-STS, TLS-RPT, DKIM and other signals.
Understand reports
DMARC aggregate reports and TLS reports are processed, deduplicated and presented as clear trends.
Report meaningful changes
Confirmed problems are grouped into incidents, showing what changed and where action is needed.
From findings to control
Technical depth. Everyday clarity.
Sendequelle separates observations, possible impact and next steps. Technical evidence remains accessible without overwhelming the interface.
Read the assessment methodology1
Verify your domain
A unique DNS record confirms ownership before active monitoring is enabled.
2
Compare stored results
Track when DNS records, certificates and policies changed. The dashboard shows stored check results.
3
Act on the cause
Confirmed changes become incidents with supporting evidence, a timeline and relevant next steps.
Ready for the next step?
Check first. Monitor when it matters.
One-time checks, including selected blocklists, are available without an account. Sign up for verification, history, regular reputation checks, alerts and teams.