Free MX Lookup Online - TestMu AI (Formerly LambdaTest)

What is an MX Lookup?

An MX Lookup (or MX record check) queries a domain's DNS for its MX (Mail Exchange) records, the servers responsible for receiving email for that domain. Each MX record has a priority value that tells sending mail servers which server to try first. This tool resolves those records in real time, right in your browser, and also resolves each mail server's IP address along with its ASN and organization.

How to Use the MX Lookup Tool

• Enter a Domain: Type the domain name you want to check (e.g., lambdatest.com). You can paste an email address or URL too, the tool extracts the domain.
• Click "MX Lookup": This queries the domain's MX records via public DNS and lists each mail server, sorted by priority.
• Review the Results: See each mail server's priority, hostname, IP address, ASN, organization, and TTL.
• Copy or Clear: Use the clipboard icon to copy the table, or the "Clear" button to start over.

Note: Enter a valid domain without prefixes like "https://" or a trailing "/". The tool normalizes common formats automatically.

Understanding MX Priority

Every MX record carries a priority value, and that number decides the order in which sending servers try your mail hosts. Here is how the priority field behaves in practice.

• A lower priority number is preferred, sending servers try it first.
• If the preferred server is unreachable, mail falls back to the next-higher priority.
• Equal priorities (e.g., two records at 5) are load-balanced between servers.
• A single Null MX record (priority 0, no host) means the domain explicitly accepts no email.
• No MX records at all means mail may fall back to the domain's A record (RFC 5321).

Why Use an MX Record Checker

An MX record check is a core step in email and DNS troubleshooting, and it pairs naturally with the other free network tools from TestMu AI such as the domain to IP lookup, hostname to IP resolver, reverse IP lookup, and IP to hostname tools. Use an MX lookup to:

• Verify that a domain's email is configured correctly
• Diagnose email delivery and bounce issues
• Confirm a migration to a new mail provider (e.g., Google Workspace, Microsoft 365)
• Check which provider hosts a domain's email
• Audit DNS as part of deliverability and security reviews

Frequently Asked Questions (FAQs)

What is an MX record?

An MX (Mail Exchange) record is a DNS record that specifies the mail servers responsible for accepting email for a domain, along with a priority value that controls the order in which they are tried.

What does the MX priority number mean?

The priority (or preference) controls the order mail servers are tried. A lower number is preferred, so sending servers attempt the lowest-priority record first and fall back to higher numbers if it is unavailable.

Why do the mail server IP addresses differ from other tools?

Large mail providers use anycast and geo-based DNS, so a mail server hostname resolves to different IP addresses depending on where and when the query runs. The hostnames and priorities are stable, but the IP and its country can vary between tools.

What does it mean if a domain has no MX records?

If a domain has no MX records, mail may fall back to its A record per RFC 5321. A single "Null MX" record (priority 0 with no host) means the domain explicitly accepts no email.

Is this MX lookup tool private?

Yes. The lookup runs entirely in your browser using public DNS-over-HTTPS. No data is stored or tracked.

How long do MX record changes take to propagate?

MX changes propagate as the old record's TTL expires, often within minutes to a few hours but up to 24 to 48 hours worldwide. Lowering the TTL before a migration makes the cutover faster.

Do MX records affect email deliverability?

Indirectly. MX records route incoming mail, while SPF, DKIM, and DMARC govern whether your outbound mail is trusted. Correct MX records plus aligned authentication records together give the best inbox placement.