IP y red

Consulta MX

A domain's mail servers: priorities, IP addresses, PTR and setup errors.

Datos clave

MX lookup online: enter a domain and see its mail servers by priority, their IP addresses, PTR and typical mistakes (MX pointing to an IP or CNAME, null MX). Free, no sign-up. This is a DNS check: we do not test SMTP connections, open relay or blacklists.

Precio: Gratis
Registro: No necesario
Procesamiento: On our server: DNS queries only (MX, A/AAAA, PTR) through the server's resolver; we never connect to your mail servers
Entrada: A domain such as example.com (a URL with http:// or www also works)
Límites: 30 checks per minute, no sign-up and no daily limit; the first 20 MX records are shown and the check has a budget of about 10 seconds
Resultado: Mail servers by priority with TTL, IPv4/IPv6 and PTR, the detected mail provider, flags (null MX, IP instead of name, CNAME, does not resolve, private IP, duplicate) and a list of problems
Última actualización: 2026-10-26

Código abierto en GitHub

Ejecuta la misma comprobación en tu propio equipo: una herramienta de línea de comandos de Node.js, una biblioteca y una GitHub Action. Código abierto con licencia MIT.

ksanyok/mx-lookup

MX record lookup: a domain's mail servers

MX records tell senders which servers accept mail for a domain and in what order. This tool queries the MX records, sorts them by priority, resolves each server to IPv4 and IPv6, looks up PTR records and the mail provider, and flags the mistakes that make mail disappear: MX pointing to an IP or a CNAME, servers with no address, private IPs, a null MX mixed with normal records.

MX servers by priority with TTL

IPv4, IPv6 and PTR for each server

Provider: Google Workspace, Microsoft 365, Zoho, Proton and more

Null MX, MX to an IP or CNAME, hosts without an address

Cómo usar

Enter a domain (or an e-mail address — we take the part after @)
Compare the servers and provider with where your mail actually lives
Fix the listed errors, then check SPF, DKIM and DMARC

FAQ

MX (Mail Exchanger) is a DNS record that lists a domain's mail servers and their priority: senders try the server with the lowest number first.

Enter the domain, such as example.com, and click Look up MX. You see the servers by priority, their IPs, PTR and any problems found.

It is a “.” record with priority 0 (RFC 7505): the domain states explicitly that it accepts no mail. A null MX next to other MX records is an error.

RFC 5321 requires a host name with an A/AAAA record. Many servers reject MX records that point to an IP or a CNAME, so mail is not delivered.

Under RFC 5321 the sender tries the domain's own A/AAAA address (an implicit MX). We show this case as a separate warning.

PromoPilot frente a alternativas: comparación

Comparamos solo lo que está confirmado en las páginas de cada servicio. Donde no pudimos confirmar un dato, la celda muestra "—".

Parámetro	PromoPilot	MxToolbox MX Lookup
MX list by priority, IP and PTR	✓	✓ MX by priority; queries the authoritative name server directly so changes show immediately
SMTP, open relay and response-time check	✗	✓ “Diagnostics”: reverse DNS, a basic open-relay test, response time
Blacklist check of MX IPs	✗	✓ each MX IP against 105 DNS blacklists

Desplaza la tabla hacia los lados

Dónde somos más débiles: no SMTP diagnostics (open relay and response time are not measured) and no blacklist check of the MX IPs.

Cuándo elegir PromoPilot: When you need to see where a domain's mail goes and whether MX mistakes block delivery, in English, Ukrainian, Russian or Polish. For SMTP diagnostics and blacklist checks use other services.

Comprobado el: 2026-10-16. "—" significa que no está confirmado en la página oficial; las condiciones y los precios cambian, así que consulta los sitios de cada servicio.