MX Lookup and Mail Domain Report

When mail doesn’t arrive or lands in spam, these two tools in the Mail category are the best place to start. MX Lookup shows which servers accept mail for a domain. The Mail-Domain-Bericht (mail domain report) runs the domain through all mail checks and sums up the result on one page.

Tool	License	What it checks
MX Lookup	free	mail servers with priority, addresses and reverse DNS
Mail-Domain-Bericht	required	MX, SPF, DMARC, DKIM, BIMI and MTA-STS/TLS-RPT

MX Lookup

Enter the domain, for example example.com, and click Prüfen (check). The app queries the MX records, resolves each mail server to its IPv4 and IPv6 addresses and looks up the PTR record (reverse DNS) for each address.

The Mailserver table shows priority, host, addresses and reverse DNS. The server with the lowest number is tried first.

Findings

Finding (as shown in the app)	Meaning and what to do
Die Domain gibt es nicht (NXDOMAIN)	The domain doesn’t exist: a typo, or it isn’t registered or delegated.
Keine MX-Records	No MX records. Mail then goes to the domain’s A/AAAA address (implicit MX). If the domain shouldn’t receive mail, set a null MX 0 . (RFC 7505).
Null-MX	The domain deliberately receives no mail. Fine if that’s intended.
MX zeigt auf eine IP-Adresse	The MX points to an IP address. An MX must be a hostname: create a hostname with an A record and use it as the MX.
… ist ein CNAME	MX targets must not be a CNAME. Enter the hostname the CNAME points to.
… hat keine Adresse	The mail server has no address and can’t be reached. Add an A or AAAA record for the host.
Kein PTR für …	No PTR for this IP. Many receivers reject mail from servers without reverse DNS. The PTR is set by whoever operates the IP, usually your hosting provider.
Nur ein MX	Note: a second mail server with a higher priority covers outages.
Mehrere MX mit gleicher Priorität	Note: several MX with the same priority share the load randomly.

Mail Domain Report

The report runs six checks in parallel: MX, SPF, DMARC, DKIM, BIMI and MTA-STS with TLS-RPT. At the top is the Übersicht (overview) table with the columns Prüfung (check), Ergebnis (result) and Wichtigster Befund (most important finding). The result is one of four levels: In Ordnung (OK), Hinweis (note), Warnung (warning) or Fehler (error).

Below that come all findings of the individual checks, each prefixed with the name of the check. If a part fails, for example because a server doesn’t answer, the report doesn’t stop. That part shows up as the finding „Prüfung fehlgeschlagen“ (check failed) and the rest carries on.

Good to know:

• In the report, DKIM searches 46 common selectors. If it finds nothing, that doesn’t mean DKIM is missing. Check again in the DKIM check with the selector from a real email.
• Blacklists aren’t part of the mail domain report. Use the blacklist check for that. The full domain report includes them along with the DNS checks.
• For the details of a single check, open the individual tool. It has more explanations and its own options.

What every check shows

All checks follow the same pattern:

• Ergebnis (result): findings with a traffic light and one sentence on what to do, followed by the tables.
• Rohdaten (raw data): every DNS response in dig format, and for HTTP fetches the server’s response too.
• Befehl (command): the dig commands to reproduce the result in the terminal.

The Exportieren (export) menu saves the report Als JSON, Als CSV or Als PDF für Kunden (as PDF for clients). The resolver button next to the input field picks which resolver this one query uses. You set the default in the settings. Below the field are your most recently checked inputs, ready to click again. If something has changed since the last run, the app shows how many findings are new or gone. More on this in Reading results.