MX Lookup

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What is a DNS MX record?

An MX record or mail exchange record, is a type of DNS record that specifies which mail servers are responsible for accepting email messages for a domain. They are essential for email delivery, as they direct incoming emails to the correct servers depending on the email service provider (e.g., Google Workspace, Microsoft 365, Zoho Mail, etc.). A domain can have multiple MX records, each with a different “priority” value.

Why do you need an MX record?

An MX record is required so the sending email server knows where to deliver a message for your domain.

Can a domain have more than one MX record?

Yes. Having multiple mail exchange records is recommended for redundancy and reliability. By configuring more than one mail server with different priority values, you establish a fallback system. If the primary mail server (the one with the lowest priority number) is offline due to maintenance, an outage, a hardware failure, or any other reason, the sending server will automatically attempt to deliver the email to the next available server on the list.

This setup prevents emails from getting lost and ensures your business can continue receiving important communications without interruption. Additionally, multiple MX records can be configured with the same priority value to distribute incoming email traffic across several servers (i.e., load balancing).

How does an MX record work?

When an email is sent, the sender’s mail server doesn’t know where to deliver it, so it queries the DNS for the recipient’s domain name (e.g., gmail.com) to find its MX record. The authoritative DNS server for that domain responds with a list of designated mail servers, each accompanied by a numerical priority value.

The sending mail server then attempts to connect to the recipient's mail server with the lowest priority number first (actually the highest priority value). If the server is unavailable, it systematically tries the next lowest-priority server until a connection is established. This system of multiple records with priorities ensures that email can still be delivered even if one mail server is down.

What are DNS MX lookups used for?

Checking a domain's MX record helps detect misconfigurations that could prevent users from receiving emails. An MX lookup tool is primarily used for diagnosing and troubleshooting email delivery issues, as it allows you to check a domain's DNS records to see which mail servers are designated to receive emails and whether they are configured correctly.

For instance, you might want to look up mail exchange records and use an MX lookup tool when emails are not being delivered, since a missing or incorrect MX record is a common cause of delivery failure. If you or your users are not receiving emails for a specific domain, the first step is to check your MX records to see if they are pointing to the correct email server.

Another instance where an MX lookup tool is needed is when you migrate your email service, such as from an on-premises server to Google Workspace or Microsoft 365. You need to update your MX records and use an MX record lookup tool to verify that the new records have been propagated and are correctly configured.

Who controls my MX record?

The domain owner has legal and administrative control over MX records. They have the power to decide who provides their DNS services and, therefore, who manages their MX records.

However, the DNS service provider is the entity that actually “controls” the records in a technical sense. This is often the same company as the domain registrar, but it can also be a separate service, such as Cloudflare or Amazon Route 53. The DNS provider's control panel lets owners log in to add, edit, or delete MX records. The records are stored on the DNS provider's name servers, which are the authoritative sources of information for that domain on the Internet.

How long does it take for a new MX record to propagate?

The time it takes for a new mail exchange record to propagate can vary. The fastest time can be 15 minutes to an hour, but it can also take as long as 24-48 hours. The exact time depends on your DNS record's time to live (TTL) value and the speed at which global DNS servers refresh their DNS caches. Even your local computer may have a DNS cache that affects MX record propagation. Even after the record has propagated globally, you may still see the old record until your local cache is cleared.

How can I look up my MX and other DNS records?

You can use this free MX lookup tool or use DNS Lookup API to retrieve your domain's MX and other DNS records, such as TXT, CNAME, PTR, and A records. Simply type in the domain name and click the Lookup button. If you only want to look up a specific record type, you can use these tools for free:

• CNAME Lookup tool
• TXT Lookup tool.